Today I have a slightly different demographic of readers of this blog than in the past, so I’ve been dredging up old posts into the light of day. This is a renamed post from September 3, 2011. I’ve changed some wording to be a bit more mellifluous if that’s even possible.
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I’ve had this notion (a conceit, really) that as someone from both academia and industry, I should reach out to my colleagues in academia in order to bring some awareness of how chemistry is conducted off-campus. After many, many conversations, an accumulating pile of work in local ACS section activities, and visits to schools, what I’ve found is not what I expected. I expected a bit more academic curiosity about how large-scale chemical manufacturing and commerce works and perhaps what life is like at a chemical plant. I’d guessed that my academic associates might be intrigued by the marvels of the global chemical manufacturing complex and product process development. Many academics would rather not get all grubby with filthy lucre. Not surprisingly, though, they already have enough to stay on top of.
What I’ve found is more along the lines of polite disinterest. I’ve sensed this all along, but I’d been trying to sustain the hope that if only I could use the right words, I might elicit some interest in how manufacturing works- that I could strike some kind of spark. But what I’ve found is just how insular the magisterium of academia really is. The walls of the fortress are very thick. I’m on a reductionist jsg right now so I’ll declare that chemistry curricula is firmly in place on the three pillars of chemistry- theory, synthesis, and analysis. In truth, textbooks often set the structure of courses. A four-year ACS certified chemistry curriculum spares only a tiny bit of room for applied science. I certainly cannot begrudge departments for structuring around that format. Professors who can include much outside the usual range of academic chemistry seem scarce.
It could easily be argued that the other magisteria of industry and government are the same way. Well, except for one niggling detail. Academia supplies educated people to the other great domains comprising society. We seem to be left with the standard academic image of what a chemical scientist should look like going deeply into the next 50 years. Professors are scholars and they produce what they best understand- more scholars in their own image. This is only natural. I’ve done a bit of it myself.
Here is my sweeping claim (imagine waving hands overhead)- on a number’s basis, chemists apparently aren’t that aware of industrial chemical synthesis as they come out of a BA/BS program. That is my conclusion based on interviewing many fresh chemistry graduates. I’ve interviewed BA/BS chemists who have had undergraduate research experience in nanomaterials and atomic force microscopy but could not draw a reaction scheme for the Fisher esterification to form ethyl acetate, much less identify the peaks on 1HNMR. As a former organic assistant prof, I find it sobering and a little unexpected.
A mechanistic understanding of carbon chemistry is one of the keepsakes of a year of sophomore organic chemistry. It is a window into the Ångstrom-scale machinations of nature. The good news is that the forgetful job candidate usually can be coached into remembering the chemistry. After a year of sophomore Orgo, most students are just glad the ordeal is over and they still may not be out of the running for medical school.
I think the apparent lack of interest in industry is because few have even the slightest idea of what is done in a chemical plant and how chemists are woven into operations.
To a large extent, the chemical industry is concerned with making stuff. So perhaps it is only natural that most academic chemists (in my limited sample set) aren’t that keen on anything greater than a superficial view of the manufacturing world. I understand this and acknowledge reality. But it is a shame that institutional inertia is so large in magnitude in this. Chemical industry needs chemists of all sorts who are willing to help rebuild and sustain manufacturing in North America. We need startups with cutting edge technology, but we also need companies who are able to produce the fine chemical items of commerce. Have you tried to find a company willing and able to do bromination in the USA lately? A great deal of small molecule manufacture has moved offshore.
Offshoring of chemical manufacturing was not led by chemists. It was conceived of by spreadsheeting MBAs, C-suite engineers and boards of directors. It has been a cost saving measure that mathematically made sense on spreadsheets and PowerPoint slide decks. The capital costs of expansion of capacity could be borne by others in exchange for supply contracts. There is nothing mathematically wrong with this idea. Afterall, corporate officers have a fiduciary responsibility to their shareholders. Allowing profit opportunities to pass by is not the way to climb the corporate ladder.
We have become dependent on foreign suppliers in key areas who have control over our raw material supply. Part of control is having manufacturing capacity and closer access to basic feedstocks.
The gap between academia and industry is mainly cultural. But it is a big gap that may not be surmountable, and I’m not sure that the parties want to mix. But, I’ll keep trying.
[Note: This post is about replacing the hydrogen atoms along the carbon backbone of a polyolefin polymer with fluorine atoms to produce a fluorocarbon surface on a finished good. Here “finished good” refers to anything from polyolefin pellets, powders, components or blow molded articles such as HDPE bottles.]
Recent news has highlighted the use of fluorinated High-Density Polyethylene (HDPE) packaging for pesticides and other products, bringing more attention to the issue of PFAS/PFOS contamination.
What we’re not talking about is a polymer made from fluorinated monomers or comonomers. This refers to a hydrocarbon HDPE bottle made from ethylene (H2C=CH2) monomer that is fluorinated after the bottle is manufactured.
What’s more, the HDPE fluorination process is said to produce PFAS/PFOS (how?) substances that can migrate. Although this technology is not new, and fluorinated hydrocarbon bottles have been around well before the widespread concern over PFAS/PFOS residues, the significance of such contamination was not fully anticipated. As a chemist, the extensive release of fluorinated low molecular weight alkyl derivatives like PFAS/PFOS came as a surprise to me despite knowing that an analogous situation with fluorinated pharmaceuticals that are getting through wastewater plants due to their resistance to microbiological decomposition. For myself only, very little concern for PFAS/PFOS pollution has been noted. You might suppose that chemists could have led the way to understanding. But, not to my knowledge.
The perfluorinated alkyl materials in question bear a close resemblance to TeflonTM which is known for its chemical inertness and lubricity. In chemistry, Teflon is usually ignored as unreactive with most chemicals, except perhaps molten alkali metals. Strategically placed fluorinated features on a molecule can lend the property of greater hydrophobicity or lipophobicity with increased electron withdrawing properties. The high electronegativity of fluorine pulls electron density towards the fluorine atoms through the sigma bonds of a molecular skeleton. Fluorinated organic acids very often have dramatically increased acidity like triflic acid, CF3SO3H, or increased alkylating reactivity like magic methyl, F-SO2(OCH3). By contrast, fluorinated carbon chains themselves are fairly unreactive and quite hydrophobic, as in water repellant. The water repellency of fluorinated hydrocarbons is a very attractive property commercially.
Below are images of the hydrocarbon hexane in ball and stick form and below in a space filling rendering. To the right is perfluorohexane and below that is its space filling rendering. Hexane is just an example of an “ordinary” hydrocarbon that could be perfluorinated.
Graphics by Sam Hill. Hexane (left) and perfluorohexane (right). As can be seen on the right, the green fluorine atoms are rendered larger than the corresponding white hydrogen atoms because fluorine atoms are larger than hydrogen atoms. In some rendering software, the space filling structures are adjusted to show where some percentage (i.e., 95 %) of the electron density is located. These renderings are by ChemSketch so God only knows how atoms are scaled.
A brief interlude on molecular polarity
Before we go on, there is the matter of polarity, dipolarity, dipolar chemical bonds and dipolar molecules. A dipolar polar chemical bond is one in which the distribution of electrons is lop-sided. That is, one atom of a chemical bond has a bit more negative charge than the other, which is thereby deficient in negative charge, or by default carrying a partial positive charge. Chemical bonds, functional groups and entire molecules can be dipolar.
But charge comes in whole numbers, so how can we talk about partial charge? A covalent chemical bond consisting of 2 atoms, same or different, will hold together because the two atoms share a pair of outer electrons. If one of the two atoms in the bond has a greater affinity for negative charge, then the cloud of 2 bonding electrons will spend a bit more time near the more electronegative atom. This shift leaves the other nucleus slightly deficient of negative charge averaged over time meaning that the positive charge of the nucleus is slightly more exposed to the world.
Graphics by Jed Klampett. Polar and nonpolar molecules.
In chemistry there is a saying- “likes dissolve likes”. This means that a polar solvent like water can more readily dissolve polar solids and may mix freely with other polar liquids. Nonpolar liquids like hydrocarbons can dissolve nonpolar solids and may mix freely with other nonpolar liquids. Amphiphilic substances have both polar and non-polar features allowing them to compatibilize polar and nonpolar molecules together. Soaps and detergents are in this category.
We should be careful here. The polar-polar and nonpolar-nonpolar solubility generalizations above are really just bookends across a vast open shelf of partial solubilities between them. Nonetheless, it is a useful rule of thumb.
So, if likes dissolve likes, and the fluorine atoms on a molecule accumulate a bit of negative charge, then why doesn’t a fully fluorinated organic molecule freely dissolve in water owing to fluorine’s negative polarity via hydrogen bonding with water’s positively polarized hydrogen atoms?
Carbon atoms can form bonds with itself or other atoms in several ways that give rise to different overall shapes.
Back to our regularly scheduled content
In situ fluorinated packaging, a niche within the packaging industry, was not something I was fully cognizant of until recently. I have come to understand that HDPE, along with numerous other polymers, can undergo treatment with elemental fluorine or fluorinated reagents to alter the hydrocarbon polymer’s C-H groups and convert them into C-F groups. This alteration gives the HDPE surface properties similar to a perfluorocarbon like Teflon™. For HDPE pesticide packaging, this fluorocarbon layer reduces the product’s permeability to the pesticide’s components. Package fluorination is all about reducing permeability of the container.
Definition: Hydrocarbon. A category of substances composed only of hydrogen (H) and carbon (C). There are 4 main sub-categories: Alkanes, alkenes, alkynes, and aromatics. A hydrocarbon can be composed of any combination of the 4. The principal mineral sources of hydrocarbons are coal, petroleum and natural gas. A hydrocarbon may also be called an organic substance, where organic refers to a carbon-based substance.
HDPE, high density polyethylene, is a hydrocarbon polymer of ethylene gas and often with various hydrocarbon comonomers. Hydrocarbon polymers, also called polyolefins, are notable for their considerably inert chemical properties. Inertness is the resistance to chemical change. However, contact with certain fluorinating agents like F2, ClF3, NF3, etc., diluted in an inert gas can, at relatively low temperatures, exchange the H atoms of HDPE with F atoms. Eventually, all or most of the H atoms on the polymer surface will be exchanged. A carbon molecule that has F atoms replacing all H atoms is said to be perfluorinated.
Pesticides are meant to be spread over selected parts of the environment to do their trick. A great many pesticides are synthetic organic chemicals so naturally there is the possibility of any given pesticide or solvent to diffuse through a hydrocarbon-based container. Migration of product molecules into the polyolefin packaging, in this case (HDPE), can result in the release of the hazardous contents and compromise the overall containment, possibly resulting in exposure to the public and the environment.
It should be possible to slow the rate of diffusion of any given hazardous material through a non-fluorinated container by simply making the container walls thicker. The polyolefin manufacturers would be in favor of this, but the converters who buy the plastic pellets to blow mold the containers may balk. Their raw material costs would rise and they would have to pass the costs to customers, who will resist the cost increase. Then with the increase in mass flow of polymer melt necessary, perhaps the throughput or required extruder torque might change unfavorably. Hard to say.
Some of the small-molecule bad actors
On March 5, 2021, EPA published the list below of PFAS/PFOS compounds found in the 20-50 ppb level in fluorinated HDPE containers used to store and transport a mosquito control pesticide product.
Abbreviated
Full Name
PFBA
Perfluoro-butanoic acid
PFPeA
Perfluoro-pentanoic acid
PFHxA
Perfluoro-hexanoic acid
PFHpA
Perfluoro-heptanoic acid
PFOA
Perfluoro-octanoic acid
PFNA
Perfluoro-nananoic acid
PFDA
Perfluoro-decanoic acid
PFUdA
Perfluoro-undecanoic acid
These are all perfluoroalkyl carboxylic acids listed by increasing chain length. Notably the terminal carbon is fully oxidized to the carboxylic acid and is not fluorinated. This acidic end gives a chemically reactive handle for further manipulation of the PFAS/PFOS if desired.
PFOA, perfluorooctanoic acid, has been industrially produced by what is now 3M since the mid-1940s. It has been used to place TeflonTM coatings on frying pans. It was originally prepared by the electrochemical fluorination (ECF) of octanoyl (ock TAN oh ill) chloride, the hydrogen saturated 8-carbon acid chloride. ECF produces the perfluorooctanoyl fluoride which is then hydrolyzed to the acid chloride liberating HF.
Perfluorination of HDPE bottles relies on the most electronegative element, diatomic fluorine gas, F2, or other similarly reactive fluorinating reagents, and does chemistry on a solid polyolefin surface. Fluorine gas is diluted in a suitably noninterfering gas like nitrogen, argon or CO2 and then exposed to the polymer of interest at a prescribed pressure, temperature and exposure time. Fluorine atoms replace hydrogen atoms on the polymer chain. According to one source, the rate of fluorination is diffusion limited. This means that the fluorination reaction is very fast. The presence of molecular oxygen with molecular fluorine had a retarding effect on fluorination proportional to the concentration of oxygen gas. The presence of oxygen led to it being incorporated onto the polymer.
Given the advantage of impermeability provided by fluorinated polyolefin articles, it is clear that there are many excellent applications of in situ fluorinated polyolefins. The replacement of glass and metal with lighter fluorinated HDPE containers may save on transportation costs on a weight basis. Whether or not the economics favor fluorinated polyolefins over glass or metal manufacturing costs kg for kg is unclear.
The range of application categories listed above is quite large. Each entry in the list has many individual components that may be subject to fluorination as well. It is no wonder that PFAS contaminants are spread widely around the world. The US EPA has issued a letter (below) to companies fluorinating HDPE to beware of accidentally producing PFAS/PFOS in their operations. Specifically warning about the connection of PFAS formation caused by the inclusion of oxygen in the fluorination process. The letter specifically cites “EPA’s 2020 long-chain perfluoroalkyl carboxylate (LCPFAC) Significant New Use Rule (SNUR) (40CFR § 721.10536), that are found to be present in or on fluorinated polyolefins may be subject to TSCA regulations and enforcement.”
“It is during certain types of fluorination (e.g., the presence of oxygen) that the manufacture of PFAS has occurred. Manufacturers (including importers), processors, distributors, users, and those that dispose of fluorinated HDPE containers should be reminded of this potential for manufacturing PFAS and comply with any applicable regulations under TSCA, as described in the next section.“
“EPA is aware of alternative fluorination processes that use fluorine gas in the presence of gaseous inerting (e.g., nitrogen) without the presence of oxygen that could reduce the potential for unintentional manufacture of PFAS. These alternative processes for fluorination of polyethylene are highlighted in the U.S. Food and Drug Administration’s (FDA) August 2021 letter on this issue as it relates to food contact articles.”
“Requirements under TSCA PFAS Significant New Use Rules. Certain PFAS, including long-chain PFAS as defined in EPA’s 2020 long-chain perfluoroalkyl carboxylate (LCPFAC) Significant New Use Rule (SNUR) (40 CFR § 721.10536), that are found to be present in or on fluorinated polyolefins may be subject to TSCA regulations and enforcement. EPA considers the manufacturing of certain PFAS from the fluorination of polyolefins to be a significant new use under TSCA. LCPFAC chemical substances present in polyolefins due to the fluorination process would be considered byproducts of the manufacturing process because they are produced during the manufacture of the fluorinated polyolefins and do not have a separate commercial intent (40 CFR § 720.3(d)). LCPFAC chemical substances that are byproducts of the manufacturing process for fluorinated polyolefins do not meet the requirements of the byproducts exemption at 40 CFR § 721.45(e)5 and are subject to significant new use notice requirements. Significant new use rules require industry to notify EPA at least 90 days before commencing the manufacturer including import or processing of subject chemical substances for a significant new use. The required significant new use notification (SNUN) initiates EPA’s evaluation of the conditions of use associated with the significant new use. Entities may not commence manufacturing (including import) or processing for the significant new use until EPA has conducted a review of the notice, made an appropriate determination on the notice, and taken such actions as are required in association with that determination. Tala R. Henry, Ph.D., Deputy Director Office of Pollution Prevention & Toxics 2022/03/24.”
Fluorination and fluoridation. What’s the difference?
So we do not make people worried about their fluoride toothpaste or their fluoridated drinking water, let’s sort this out. Toothpaste and drinking water have a soluble ionic fluoride salt like sodium fluoride, NaF, or sodium monofluorophosphate, sodium MFP or chemically Na2PO3F. Sodium MFP is water soluble but not stable in water. It hydrolyzes to release fluoride by displacement by water to form dibasic phosphate. The MFP hydrolysis reaction is: PO3F2− + HO– → HPO42− + F−. The fluoride anion, F–, is not nearly the same as fluorine gas, F2. The F– ion bumps into tooth enamel where it binds tightly with calcium in the tooth: Ca5(PO4)3+(aq) + F−(aq) → Ca5(PO4)3F(s). This is the context in which the word “fluoridation” is used. Fluoride ions bond tightly to calcium++ ions in general. Fluoridation is just a specialized variety of fluorination and is mostly confined to the area of water treatment and toothpaste.
Fluorination is a chemical process wherein fluorine atoms are added to chemical compounds. Contact between organic substances and pure elemental fluorine gas is extremely exothermic and sometimes explosive. The dilution of F2 gas with an inert gas like nitrogen, helium or argon has a thermal safety component as well.
Polymer fluorinationout in the world- Patents
One source of manufacturing information about proprietary articles and processes is the US Patent and Trademark Office, USPTO. In order to secure your legal right to a patent, the patent applicant must disclose the exact art that is being claimed. This is because the world must have a fair chance to avoid infringement. Google Patents provides the exact text of individual patents, US and others. It also provides a timeline showing the ownership of the patent and whether or not the patent is active, expired or abandoned. Google patents also provide links to patents cited in the patent and patents that have cited the instant example.
Being a Google product, Google Patents has extensive and flexible search capacity. Rather than attempt to make a list, it is a better use of the reader’s time to go to the site yourselves and explore. Note that a search will find patents from all over the world as well as patent applications. Google patent provides a English translated version of the patent.
In searching for patents claiming compositions and methods around the fluorination of polymers, more than a few patents can be found. One can search for patents using the USPTO website (obviously) or from Google Patents.
Another good place to look for relevant art is from a patent you have already pulled up in Google Patents. Near the bottom of the patent from Google Patents is a section labeled “Patent Citations.” This section list prior art patents disclosed by the assignee and those found by the patent examiner in the course of the examination process. Prior art is disclosed by the assignee in the granted patent as well, but in Google Patents there are hotlinks to patents to aid the convenience factor.
In situ fluorination
There are companies who will fluorinate the surface(s) of High-Density PolyEthylene (HDPE) and PolyPropylene (PP) containers. HDPE and PP are especially of interest owing to their utility in packaging liquids. These two polymer classes have great rigidity and strength and are in wide use. However, they share certain weaknesses such as air permeability and permeability of the contents. Air permeability is highly undesired in food packaging as it allows for reduced shelf life or customer satisfaction with the contents. Food and drugs may be susceptible to air degradation and possible reduction of shelf life.
Note: The expiration date on a product does not necessarily mean that the product will go bad when that date arrives. The day after the expiration date is that date at which the manufacturer/seller will no longer guarantee “freshness” or some other type of quality. For instance, normal pasteurized milk is not sterile. Pasteurized milk should be good up to 1 week past the code date as long as it has not been allowed to warm up or been contaminated. Once the milk has warmed to room temperature, the normal bacteria loading will enter log-phase growth and could spoil within 1 day.
In situ fluorination is process wherein hydrocarbon polymer containers are exposed to diluted fluorine gas at a specified temperature for a specified time. At the surface hydrogen atoms along the length of the polymer are replaced with fluorine atoms. The result is a polymer along the surface which resembles TeflonTM to some extent. Some of the desirable properties of TeflonTM are then taken on by the HDPE or PP surface. This H/F exchange at the surface does not affect the properties of the base polymer.
There is one caveat, however. The fluorination must be performed with the exclusion of oxygen. One source says that the vacuum chamber in which the fluorination will take place must be pumped down to 0.1 Torr of residual air prior to exposure to fluorene gas.
Fluorination patents
Below us from the description in US5274049A Filing date 1991-07-19, Application filed by SHAMBAN WILLIAM S, W S SHAMBAN AND Co.
A method for the direct fluorination of elastomers “in order to reduce the static and dynamic friction characteristics and to increase the wear life and abrasion resistance of the elastomers. The invention also relates to elastomeric articles modified by the fluorination method.”
“What is claimed is:
1. A method of producing fluorinated elastomeric articles, consisting essentially of the following steps:
providing an elastomeric article, said elastomeric article comprising an elastomeric polymer having a backbone chain having a plurality of hydrogen atoms attached thereto;and
exposing said elastomeric article to gaseous fluorine under conditions sufficient to reduce the friction coefficient of said article without promoting degradation of the tensile properties of said article.”
Claim 8 claims a method using a hydrogen fluoride scavenger …
“8. A method for producing a fluorinated elastomeric article having a reduced coefficient of friction, comprising the steps of:
placing a thermoset elastomeric article and a hydrogen fluoride scavenger in a closed reactor vessel, said thermoset elastomeric article comprising an elastomeric base polymer having a backbone chain, said backbone chain including sufficient carbon atoms having replaceable aliphatic carbon-hydrogen bonds so that a fluorinated matrix of said fluorinated elastomeric article reduces said coefficient of friction;”
In the description the patent cites sodium fluoride, NaF, as an HF scavenger wherein NaF + HF => Na[HF2], sodium bifluoride.
Inhance Technologies LLC filed application US20190040219A1, but it was later it was abandoned due to failure to respond to an office action. The application claimed a multistep method for fluorinating elastomeric workpieces with 20 % F2 in nitrogen and “altering certain mechanical properties such as tensile property [and] the elastic modulus, an impact property, a wear property, etc.“
Systems and methods for processing fluoropolymer materials and related workpieces, US11879025, filed 2021-04-23, Current Assignee: Inhance Technologies LLC. Claims method of removing perfluorinated compounds from fluoropolymers. The core of the art involves placing a fluoropolymer work piece in a thoroughly deoxygenated chamber, heated from 25 C to 300 C and exposed to a fluorinating atmosphere such as F2/N2 for specified time period. This treatment is claimed to remove fluorocarbons like PFOA to non-detectable levels. There is no mention of where the PFOA goes afterwards, but it looks promising if accurate. However, the granted patent is off-limits for 20 years unless a license is obtained or some other arrangement is made.
Fluorination is imbedded deeply into the design of a great many articles of commerce. The water repellency of perfluorinated polymers in fabrics is one of the chief applications of fluorinated organic materials. The inherent lubricity of PTFE, its built-in chemical inertness and its hydrophobicity have ingratiated millions of consumers and have met performance expectations world wide.
Perfluorinated foams for fire protection in aircraft hangers and industrial spaces are valuable for their ability to float on the surface of burning liquid fuels, blanketing the surface as a vapor and oxygen barrier. The suppression of flammable volatiles in a fire by a layer of protective foam can inhibit flashover of the fire, reducing the overall damage of a fire. The fire retardancy of perfluorinated substances inhibits their combustion and discourages continued burning when the flame source is removed. Halogens as a group have been used for fire retardancy and with bromine in particular.
The chemical origin of the fire retardancy properties of perfluorinated organic materials lies in the low reactivity of the -CF2– fluorine atoms with oxygen. In the combustion of hydrocarbons, hydrogen atoms are readily removed by oxygen or radical species to form water. The C-F bond is one of the strongest bonds in organic chemistry and is slow to be removed by oxygen.
Drug molecules are frequently fluorinated in particular locations on the drug molecule. A C-F bond resists catabolic degradation and enhances the local hydrophobicity of the drug allowing for greater half-life and enhanced drug potency. The down side is the resistance to catabolic degradation and excretion. Many drug molecules are released intact into sewage treatment facilities where they also resist degradation, possibly due in part to the fluorinated features. The effect is that fish and other organisms are exposed to the drug. As with humans, fish and other creatures of the waterways and soil did not evolve with biochemical mechanisms to deal with fluorinated organics.
In the in situ fluorination process, PFAS/PFOS side products can form, especially when oxygen is present. This can be monitored by quality control but companies will comply with recommended PFAS/PFOS best practices only if there are regulations or the threat of them. Nations regulating PFAS/PFOS contamination will have to compete with nations who do not impose regulations. This is the usual scenario for nations with heavy reliance on imported articles but uneven regulation.
The state of Nevada is quickly becoming the leading source of lithium in the USA and beyond. In the state there will soon be three major types of lithium ore beneficiation- Brine evaporation, hard rock extraction and lithium clay extraction. Nevada already has in excess of 180,000 active mining claims amounting to 49 % of the total BLM national inventory. In addition to this, Nevada has “198 authorized mining plans of operations, and 282 active exploration notices.” Nevada has a long history of fruitful gold and silver mining.
Nevada had earlier won the gold deposit lottery with the Carlin Trend occupying much of the northwestern section of the state. The Carlin Trend has become an archetype in gold mining. These deposits are often described as Carlin-type “invisible gold” ore deposits. Such a deposit is characterized as sediment hosted and disseminated [Editor: disseminated seems like a bummer]. Gold in such deposits are typically invisible and often only detected by lab analysis. According to Wikipedia, most of the gold mines in the Great Basin of the western US are of the Carlin-type.
But, enough about gold and on to lithium
After 6 years of regulatory scrutiny, a new lithium-boron open-pit mining operation in Nevada operated by Australian mining company ioneer has just been approved by the Bureau of Land Management, BLM, for Rhyolite Ridge. The mine is located in the Basin and Range Province near the southwest border of Nevada and California.
The old joke used to be that a mine is a hole in the ground with a liar standing at the top. With the independent economic evaluations available today as part of the disclosure to investors, the likelihood of being duped by fake or salted deposits has dropped considerably. However, the market value of the ore in the future is still subject rapid and unpredictable change.
If you find yourself flying over Nevada on a clear day, you can easily see the basin and range features of the terrain. Nevada occupies only a small part of the total area. The basin and range province extends north to the Columbia Plateau and south into the Central Mexican Plateau.
A very small part of Nevada’s basin and range landscape as viewed from above the Rhyolite Ridge area in Nevada. Image from Google Maps.
The Basin and Range Province of North America. Image from Wikipedia.
Rhyolite Ridge Lithium-Boron Project
The BLM approval opened up $1.19 billion of potential funding of which $700 million is from a US government loan. According to Mining.com, Rhyolite Ridge is the first new lithium mine in 60 years and the first new boron mine in the last century in the US. [Note: I have to assume “new” means new hard rock mineas opposed to brines or evaporites] While the approval by BLM has opened some doors to funds, not everyone is convinced of the major investor’s liquidity.
So, what is rhyolite?
I can’t improve on the definition found in Wikipedia, so I’ll just quote it with the links intact-
If you have ever seen molten glass and noticed its high viscosity, this gives an idea of what high silica content does to lava. The higher viscosity provided by the silica component suppresses the release of gases until nearer the surface where they are released as bubbles with vigor. It is very much like a comparison between boiling pasta water and boiling marinara sauce. The marinara sauce spatters badly due to its viscosity but the pasta water just does a rolling boil.
Source: Mashed.com. Spattering is a universal behavior of hot, gassy fluids. In this case the gas is steam. Magma also contains steam.
The Rhyolite Ridge lithium-boron (LiB) deposit is said by some to be the only known LiB deposit in the US and only one of two known in the world.
“The Rhyolite Ridge mine will run for 22 years. It will produce 22,000 tonnes of lithium carbonate a year. That’s enough to power 370,000 electric vehicles. It will also produce 170,000 tonnes of boric acid, according to the company. The boron contributes 30% to 40% of the mine’s revenue, providing a buffer against lithium market volatility.” –Mining.com
Around the world new economic lithium deposits are being discovered now and then, and a few are being readied for mining. It was announced recently that BLM has approved operations at the Rhyolite Ridge Lithium-Boron Project in southwestern Nevada.
What is interesting about this Rhyolite Ridge project is that it aims to produce both lithium and boron. I’m not an engineer so maybe I’m overly impressed, but the processing plant they propose seems very clever. They will produce their own sulfuric acid from sulfur and extract waste heat for use in generating steam for evaporation of the extracts and electricity. They are completely off the energy grid.
The extracted ore, now called ROM or run-of-mine, is transported to the plant straight from the mine and sized by crushing to 20 mm pieces. The crushed ROM is then taken to a series of sulfuric acid extraction vats and leached for ~ 7 days. The pregnant leach solution containing the lithium, boron and soluble impurities is then taken to evaporators with repeated crystallizations and, using differential solubility, separates the lithium component from the boric acid. In the end they produce lithium carbonate. The video does show a soda ash (sodium carbonate), Na2CO3, silo so I assume that is where the carbonate comes from to produce lithium carbonate, Li2CO3 and to neutralize residual sulfuric acid.
Silver Peak Lithium Brine
Of interest is the nearby Silver Peak lithium brine operation operated by Albemarle just a few miles to the north of Rhyolite Ridge. The Google Maps image below shows the evaporation ponds at the Silver Peak lithium operation. Silver Peak produces both technical grade lithium carbonate and lithium hydroxide.
Image from the Operational Land Imager-2 (OLI-2) on NASAs Landsat 9. A view from space of the Silver Peak lithium brine evaporation ponds in SW Nevada.
McDermitt Caldera: Thacker pass
Another large lithium deposit was discovered in the McDermitt Caldera along the Nevada-Oregon border. Within the caldera is the Thacker Pass Lithium Mine. This lithium deposit was approved for open-pit mining by BLM on January 15, 2021, though it has been plagued by protests and an injunction. As with the rest of the McDermitt Caldera lithium, the Thacker Pass lithium is described as a lithium rich clay deposit. This is unique for lithium mines since brine extraction and hard rock mining of spodumene have been the norm. Thacker Pass’ lithium deposit is the largest known volcano sedimentary deposit in the US at an average grade of 0.22 %.
In 2023 GM invested $650 million in the Canadian Lithium Americas Corp. The Thacker pass operation is through its wholly owned subsidiary Nevada Lithium, LLC, which is responsible for production. Car giant GM’s investment gives them exclusive access through the first phase of production. Lithium Americans has received a conditional approval for a $2.2 billion loan from the US Department of Energy.
The Thacker Pass measured and indicated lithium resources are 13.7 million tons of lithium carbonate equivalent. Lithium Americas calculates that the recoverable lithium is worth $3.9 billion.
Interestingly, the McDermitt Caldera is possibly the oldest of a sequence of calderas produced by the Yellowstone Hotspot. The McDermitt Caldera amounts to a lava dome that collapsed ~16.4 million years ago forming a large caldera within which several smaller calderas have formed and in which later filled with water forming a lake over the tuffaceous ash. Over time the lake produced sediments that were deposited on the floor of the lake. The source rock is rhyolite which is usually the case in the state.
The Yellowstone hotspot stays relatively constant while the crust moves over it, leaving a trail of calderas and a record of volcanic activity on the surface behind. The McDermitt caldera is labeled ’16’. Source: National Park Service.
Briefly, the lithium clay is excavated, gravel and rocks are removed, and the clay is suspended in water to form a slurry. The slurry is leached by adding sulfuric acid that is produced on-site and the lithium in the ore is extracted into the acidic liquor. Finally, the dissolved lithium is recovered as lithium carbonate and lithium hydroxide. Gangue material is deposited back into the excavated sections of the mine.
The McDermitt caldera contains many breccia and fracture zones and associated with these are deposits of other metal ores. Specifically, mercury from cinnabar ore bodies and uranium from autunite (uranyl, U6+) (Ca(UO2)2(PO4)2·10–12H2O) and pitchblende (uranate, UO2, U4+) ore bodies. Mercury reserves in the caldera, according to USGS, are estimated to be 400,000 flasks.
A Mercurial Rambling
Mercury has been packaged (and still is) at 76 pounds to the flask. This measure got its name from the mining and smelting of cinnabar in the mountains of Peru. One site was particularly rich- Huancavelica, Peru. The Spaniards had known prior to their arrival to the New World that liquid mercury could dissolve gold from ore to produce what we now know as a mercury amalgam. With very strong heating the mercury could be driven off as vapor to recover the precious metal.
Spain had its own cinnabar mine in what is now Almadén, Spain, which produced over 250,000 tonnes of mercury. The Spaniards had considerable experience with mining, refining and using mercury prior to discovery of it in the new world. Mercury was quite valuable to the Spaniards but they were faced with transporting it from, say, Huancavelica, Peru, to the Carribean coast where their ships could load the mercury and distribute elsewhere. Anecdotally, it has been estimated that for every ounce of gold produced in the new world, ten ounces of mercury were consumed.
Luckily for the 49er gold rush miners, cinnabar had previously been discovered in California. You can actually visit the old New Almaden mine museum south of the Bay Area. It is worth a trip if you are in the area.
The Spaniards figured that a man could carry what turned out to be as much as 76 lbs of mercury through difficult terrain to the Caribbean coast. Even better for the Spaniards, they knew how much gold could be extracted per pound (or whatever unit) of the mercury they dispensed. This gave them an idea of how much gold to expect and closer control of the mines. By controlling mercury, they controlled who could use it for mining and how much gold they could recover.
Back to lithium
As of this writing, Albemarle is the largest producer of lithium in the US. But the largest known deposit in the US is at Thacker Pass. The Albemarle Silver Peak lithium brine operation is legally defined as placer mining whereas the Thacker Pass operation is lode mining. The word ‘legally’ is used because any claims filed are restricted to placer or lode mining- one does not transfer to the other.
A Word or Two About Rhyolite
Rhyolite is a type of volcanic rock characterized as a ‘fine-grained extrusive igneous rock‘. Its color can vary from pale light grey to pinkish when composed of mainly quartz and feldspar or dark when of a mafic, low silicate composition was present. A quiet eruption of lava gives a solid, denser rhyolite whereas in an explosive eruption can produce the vesicular pumice. The lower density of pumice allows it to float on water. Erupting volcanic islands can produce floating rafts of pumice in the nearby waters. As magma rises in the throat of a volcano, the pressure drops and dissolved gases can form bubbles which, if they fail to disengage from the magma completely, can be ejected into the cooler air and freeze into ‘foamy’ structure. [Note: the word ‘foamy’ is my own and earth science people cannot be blamedfor this.]
A Bit More About McDermitt Caldera
The United States Geological Survey (USGS) published open-file report 76-535 in 1976 titled Geology and Ore Deposits of the McDermitt Caldera, Nevada-Oregon. A 1978 USGS open-file report by Newmont Exploration, Ltd., 78-926, James J. Rytuba and Richard K. Glanzman, Relation of Mercury, Uranium and Lithium Deposits to the McDermitt Caldera Complex, Nevada-Oregon, goes into greater detail on the three minerals.
What can a chemist possibly have to say that could be even marginally interesting about extraterrestrial life or evolution? Well, as far as extraterrestrial life and the search for it goes, I would say that all of the metallurgy, semiconductor fabrication, liquid hydrocarbon fuels, chemicals, transportation technology or polymers exploited in radio or optical astronomy, have some element of chemistry in their manufacture.
………………..
The quest to discover life beyond Earth captivates many in the broad field of space science. The Search for Extraterrestrial Intelligence (SETI) has played a significant role in astronomy and space science communities. However, the search extends beyond intelligent life; any form of life or even the essential components and conditions conducive to life, are of keen interest.
It is widely accepted that the physics governing our planet and solar system likely applies universally. While this is a hypothesis, it is a reasonable one. If the physics are consistent, then the chemistry should be as well. Consequently, the behavior and limitations associated with matter would be uniform across the cosmos. This reasoning suggests that life elsewhere in the universe would be governed by the same chemical and quantum mechanical principles familiar to us.
The “Anthropic Principle” has caused much debate, with Wikipedia noting that “Anthropic reasoning is often employed to address the notion that the universe appears to be precisely calibrated for life.” The mystery of why numerous physical constants and their ratios needed to be exactly as they are for life to emerge on Earth has intrigued many.
To say the Big Bang’s initial pressure and temperature were high is an understatement. As the universe expanded and cooled, energy barriers emerged that shaped the interactions of matter and of photons, placing boundaries on the spontaneous transformation behavior of matter. Pathways of interaction emerged, steering transformations towards increasingly specific outcomes. Essentially, it’s basic kinetics: the quickest transformations and their stable products start to prevail and fill the universe.
If physical constants are emergent at the moment of the Big Bang and become manifest down the timeline, could it be that another Big Bang could happen that is not conducive to life? There would be nobody there to ponder these questions. Life is here because it was possible and maybe even likely here and there.
The phrase “finely tuned for the existence of life” seems to leave open a crack for a creationist view. Absent the many spooky bronze and iron-age theories still in practice today, naturally a sentient being can look at her/his/its existence and marvel at how beautifully synchronized and proportioned the machinery of the universe is. Certainly, there must be a hidden message in this, right?
ET? What th’ …?
Animals like mammals, birds, fish, and even some invertebrates like octopi and crabs are considered to be sentient. According to Google, sentient animals are those that can experience feelings and sensations, both positive and negative, like pleasure, pain, joy, and fear. So, while an octopus may have elements of sentience, could distant observers elsewhere in the galaxy detect them from optical or radio astronomy techniques? Try as it might, the ability of an octopus to construct a powerful radio transmitter and beam a message into the cosmos is sorely limited by its physical anatomy. Except for humans, no other sentient life form on Earth is known to construct a radio transmitter that would serve as a beacon of sentient life.
Until recent history, SETI was limited by the lack of technology to light up the universe with our own signals or to detect faint manufactured signals across interstellar space. At such point that metallurgy, electrical engineering and the hundreds of other critical and apex technologies bloomed into a sufficient state of development, no intelligent emanations from Earth found their way into space.
While TV and radio broadcasts began their journey into space, it is important to realize that our signals were encoded onto carrier waves. Amplitude modulation (AM) signals carry their information by simply varying the magnitude of a single frequency in time with the human voice or music. This is most likely to be grasped by alien radio astronomers. Frequency modulation (FM) is a bit more challenging because audio signal is mixed with a carrier signal by a heterodyne circuit. Extracting useful information would require them to pull audio frequency information from the heterodyned signal.
Television is much more difficult. While the alien radio astronomers may have figured out FM encoded radio information, the particular details of the TV raster scan are based how human engineers decided to interlace and sequence scans to produce an image on a screen of a particular aspect ratio. TV designers took advantage of the human’s persistence of vision to seamlessly follow moving pictures to give continuous images yet maintaining a fast enough frame rate to avoid flickering. The television’s electronic timing is based on frame rate, the number of interlaced lines, and the aspect ratio of the screen.
The point of this TV discussion is that a TV signal must be deconvoluted into a signal that properly displays an image and plays the sound on a particular piece of equipment. This could be challenging for an alien radio astronomy research group to decode.
All of this talk about an octopus developing radio astronomy presupposes that its unique octopussian sentience includes such desires.
It could be that the initial energy at t = 0 yielding the primordial plasma constituting the early Big Bang was only capable of producing a specific set of fields producing elementary particles which then give way to a specific set of quantitative relationships and properties. The burst of energy causing the Big Bang must have had constraints driving its transformation into matter, which is also constrained by quantum mechanics, etc. Maybe the present universe is simply what primordial energy naturally does when expanding as a universe. Why do the quantitative values of physical constants need to be variable? An imaginary and feverish conundrum.
As the highly energized primordial plasma of the Big Bang began to cool, matter and energy channeled into particular states. The particle energy states that had the highest barriers coalesced first followed by subsequent lower energy plasma condensing into other particles. I’m drawing a crude analogy to the process where individual minerals form from cooling magma according to their melting points.
There is a notion prevalent among Creationists that the probability of a life form spontaneously forming from individual atoms is 1 in 10large or some other inconceivably miniscule chance. And if that was how life had to form, then the Earth would still be a sterile wet rock. But that is not how chemical transformations work.
Central to the Creationist view is that evolution cannot happen because there is nothing but random chance to guide the molecules of life into a highly complex organism. They start with the assumption that life arose purely from random chance. I hope to show that this assumption is false.
All atoms and molecules have properties that either qualify or disqualify them as a candidate for a given atomic or molecular transformation. All molecules have properties that either qualify or disqualify them to take part in a transformation resulting in a given product. The words “qualify” or “disqualify” could mean that something will or will not happen absolutely. But just as likely, the words could mean that a transformation is just too slow at a given temperature to give the desired effect. As it happens, temperature is critically important to molecular transformations. At a low enough temperature, most transformations will slow to a negligeable rate, shutting down that particular transformation channel. In general, where there are competing transformation channels, the fastest channel will prevail in producing its product.
All molecules have a limited set of reaction channels at a given temperature as a result of their particular reactivity.
What we think of as ‘ordinary’ chemistry is more precisely the electronic behavior of valence electrons. Nuclear chemistry also exists but in the domain of nuclear change.
Valence electrons on earth will behave the same everywhere in comparable conditions. Chemistry happens at the outer, valence level of ions, atoms and molecules. So, we should expect that bond forming and bond breaking mechanisms should be the same throughout. All of this leads to the high likelihood that chemical reaction mechanisms elsewhere in the universe should not be unfamiliar to Earthlings in general.
Life on earth exists as a result of the behavior of particular chemical substances within a range of chemical and thermal environments. The range of chemical environments and substances present during the initiation of life is thought to be quite different than what we find on earth at the present time. For instance, gas phase molecular oxygen was not present until a considerable time after life began. The initiation of life on earth was under anaerobic conditions and was able to start and survive with the materials at hand. Biochemistry is a series of reduction/oxidation events driven by the Gibbs energy of a transformation as is all of chemistry. Even on anoxic earth, diverse oxidizers were present.
Today, anaerobes are known to use the oxidative properties of inorganic species like sulfate (SO42-), nitrate (NO3-), ferric iron (Fe3+), carbon dioxide (CO2) and manganese (Mn 4+). Other anaerobic oxidants include chromate (CrO42-) and arsenate (AsO43-) which may have been present as well. Reductants include nitrite (NO2-), ferrous iron (Fe2+), and sulfide (S2-).
Oxygen is the third most abundant element in the universe and the second most abundant heavy element on earth behind iron. Many elements are strongly attracted to the abundant oxygen so it is no wonder that so many minerals are oxides of one sort or another. Oxyanions like silicates, carbonates, sulfate, nitrate, and oxides like CO2 or any number of metal oxides all contain oxygen that has been bound with another element. The oxygen pulls negative charge away from the central element making it electron deficient. In the case of sulfate and others, the actual oxidizing part is the atom with the oxygens attached, in this case the sulfur.
The presence of life on Earth means that there is a “habitable zone in parameter space“. All of the parameters affecting biochemistry must align in such a way that a zone of allowable chemical and physical conditions will exist. Many things must exist simultaneously such as the many properties and abundances of chemical substances, a suitable atmospheric composition and pressure, a planetary temperature range allowing for the presence of liquid water and the presence of sufficiently reactive organic molecules.
Not every transformation of matter is within reach in a given condition. Chemical reactivity which comprises kinetics and thermodynamics has the effect of channeling matter into a finite number of probable pathways. This bestows the property of selectivity. For any given chemical substance, only a certain limited group of transformations are possible or likely, given the conditions.
Life as we know it exists because our biomolecules were robust enough to survive their chemical and thermal environments, but not so robust that they resist the needed transformations. Life depends on biomolecules being moderately stable but not by too much. Biomolecules can organize into particular structures that are physically robust, like the chitin shells on shellfish. In the chemistry of life, chemical transformations must be tolerant of the aqueous environment in and around an organism, but not so tolerant that the necessary reactions are too slow or too fast within the narrow range of environmental temperatures available.
Organisms on earth are tolerant of water at the level of molecules. The internal apparatus of the cell is an aqueous environment having some amount of viscosity. In order for molecules to interact, they must collide with each other. Life in the solid phase would mean that biomolecules would be immobilized and unable to collide and react. Cell structure for metabolism and reproduction would not be feasible. Life in the gas phase is limited by the vapor pressure of the necessary substances. Many, if not most, biomolecules would not tolerate the heat necessary to volatilize. They would decompose.
A diversion into molecular evolution.
I’ll just blurt it out- ongoing evolution requires heritable change in a genome. A genetic change must be survivable for the parent cell to reproduce and produce viable daughter cells. The inherited mutation must not be deleterious to further reproductions of the subsequent generations. A mutation may randomly result in something that has either a lethal effect, no effect, or produces some biomolecular improvement. The mutation may be as modest as an enzyme alteration causing it to bind either more or less tightly to a ligand resulting in a few percent change in rate of some the enzyme’s function. This could translate into better efficiency in producing some cell structure or better use of energy. It could also be that nothing changes as a result of the efficiency alteration, or that it has an overall negative effect further challenging the survival of the cell line in a nonlethal way.
There are two kinds of changes that can occur with DNA. One is a change in the sequence of the DNA molecule itself. The other kind is “epigenetic” which is heritance not reliant on changes on the DNA sequence.
Creationists like to make a show of the probability of random chance producing even simple ordered sequences as fantastically small. Actually, their superficial analysis of permutations and probability looks plausible. I can’t argue with the low probability of individual atoms coming together randomly to form a living organism all at once. However, the beginning assumptions are wrong. Life did not spontaneously form out of a bunch of loose atoms by simply condensing into a centipede or a human. Change in evolution happens at the molecular level a step at a time. A change in the amino acid sequence of any given enzyme must trace back to a change in the DNA sequence to pass along a heritable mutation. Evolution moves by fits and starts. A mutation may have no effect, advantageous effect or deadly effect.
At the level of molecules, change happens through very definite chemical mechanisms. Molecules are constrained to do certain things and in a particular way. It’s like a channel. Sometimes two or more channels may be possible. In this case, the fastest channel will dominate in output and influence. An evolutionary change might cause a biochemical transformation to stop, speed up, slow down, or be more or less specific in outcome.
Molecular bonds vibrate in the range of 1013 to 1014 Hertz. A hydrogen molecule will reportedly undergo 2.5 x 1010 collisions per second at 2 bar and 24 oC. If two atoms or molecules are to react, then they must collide. At a given temperature, a collection of hydrogen atoms will be dispersed over a statistical distribution of energies.
Biochemistry on earth has evolved around water and takes advantage of certain properties of water. Its ability to hydrogen-bond is exploited extensively in biomolecule structures. Water has the ability to accommodate charged species or neutral dipolar species. This is called hydrophilicity. It is important not just to keep ions and molecules in solution, but also to stabilize the transition of a reaction if it generates a momentary dipole.
Water is immiscible with substances having a large hydrocarbon protuberances like fatty acids, phospholipids or certain side groups found on a few amino acids. This is called hydrophobicity. Terrestrial biochemistry exploits both hydrophilicity and hydrophobicity.
A benefit of hydrophobicity in biochemistry is that fatty substances like phospholipids will spontaneously organize into the lipid bilayer structure. Hydrophobicity in this case leads to the formation of stable compartmental structures. Life takes full advantage of the lipid bilayer in the production of the cell wall. This keeps all of the necessary biomolecules contained and concentrated for effective and timely biochemical transformations to occur. The cell wall excludes a great many deleterious substances as well. However, many protein structures have sections that are sufficiently hydrophobic as to be compatible with the hydrophobic lipid part of the bilayer. This property allows the protein to anchor itself within the bilayer leaving the more hydrophilic portions of the protein jutting out into the extra- and intracellular aqueous media. Many of these proteins penetrating the bilayer- channel proteins- are sufficiently hollow as to allow ions or molecules to pass through. Even better, the ability to pass ions or molecules through can be switched on or off by other biomolecules or with drugs.
Some larger molecules like the fatty phospholipids above have both hydrophilic and hydrophobic regions. Given the chance, phospholipid molecules will spontaneously orient themselves in a way that when combined the water ‘repellant’ hydrophobic tails will tend do aggregate. This leaves the hydrophilic phosphate features at each end to remain in contact with the water environment.
Cells have compartmentalization and cell walls simply because of the incompatibility of the polar water molecule and nonpolar hydrocarbons. These two incompatible liquids arrange in a way that minimizes the surface area of contact between them. They will form layers when stationary or droplets when one is dispersed in the other. This is the minimum energy condition they spontaneously go to. Micelles will even form spontaneously in your soapy dishwater.
Life on earth presently requires many environmental conditions to be just right. Cells of micellar-like construction take advantage of the hydrophobicity of substances with long chain hydrocarbon parts on one end and charged or polar features on the other side. Micelles are structures that spontaneously form in water. Living cells adopt a bilayer structure based upon the tendency for “likes to dissolve likes.” That is, non-polar hydrocarbon features “prefer” not to be in contact with polarized water, but rather cluster in a way that minimizes water-hydrocarbon surface contact. The effect of carbon chain structures in the biochemistry of earth is the stability of carbon-based structures and the wide variety features it can accommodate. These features include stable carbon-carbon chains as well as carbon bonds to hydrogen (H), nitrogen (N), oxygen (O) and sulfur (S) in particular. Carbon is unique in that it readily allows the formation of stable double bonds with itself or N, O, or S. Carbon also can form triple bonds with itself or N. Cyanide and acetylene are examples. The ease and stability of carbon bonded to C, N, O and S, along with the stability of multiple bonds on carbon all point to it as an excellent candidate for as the ideal building block for biomolecules.
It is often mentioned that since silicon has certain similarities to carbon why isn’t life based on it? Silicon-silicon bonds are prone to oxidation and not found in nature. Silicon is almost always found in nature as silicate in its various forms in minerals and very often in variety of silicate oligomers and polymers. Silicon-nitrogen and silicon-sulfur substances are not easy energetically. Furthermore, silicon does not form double bonds with itself or other elements. So, the variety of structural motifs silicon can form isn’t as broad as carbon. Silicon vastly prefers to be silicate in nature. Silicon is not found in biomolecules despite its high abundance in the nature.
Conclusion
I’m trying to make the point that extraterrestrial life will surely be different from life on earth at the macroscopic scale but maybe not so much at the level of molecular transformations. Every living species today trails behind it a unique evolutionary history, some of which remains in their genomes. Despite the huge variety of life forms on earth and all of the attendant structural variability that goes with it, we all share the use of DNA/RNA, proteins, carbohydrates, phosphates, lipids, calcium, magnesium, potassium, sodium, etc. All life forms on earth are able to capture and use energy as well as reproduce.
The history of life reveals an obstacle course through which organisms struggled to stay alive. Those that did survive had no way to anticipate the future and no way to prepare for it even if they were able to “anticipate” at all. The history of life is the history of challenges to survival.
Humans exist today because our ancestors going back into deep time were able to survive both anaerobic and oxygenated earth, snowball earth, competitive pressures from other life forms, vulcanism, cometary impact, solar UV radiation, chemical toxicity from the environment, disease and climate.
Today we can add stupidity to the list of survival challenges. Can we survive the results of our behavior? Humans have a brilliant streak in developing weapons- explosives, guns, nuclear, biological and chemical weapons. If all else fails, there will always be the sharp stick and club.
Humans are the way we are because of the way that natural history unfolded. A planet with the same makeup and conditions 3 billion years ago would evolve life in a different way than we went. Evolution happens because of the ability of our genetic material to be just a bit unstable and to be passed on in reproduction. But this change is a random process in both features and time. A genetic change can be fatal or helpful. The manner and schedule in which random genetic alterations happen is impossible to predict. Evolution is blind going forward. Another try at evolution is highly unlikely to produce Homo sapiens again.
Any given “intelligent” species may or may not invent or use radio technology. Therefore, they may or may not emit or receive radio transmissions. Such creatures would be undetectable using radio astronomy. Although two patents for wireless telegraphy came out in 1872, humans have only had useable wireless telegraphy since 1895 (Marconi). As of this writing, only 128 years have elapsed since Marconi sent his first long distance (1.5 mile) radio communication.
We have only had radio communications for 128 years in the entire history of our species. In order to have this invention in 1895, the European enlightenment had to happen leading to the idea of scientific inquiry and a minimum understanding of physics and chemistry. The voltaic pile had to be invented which gave way to further refinement of electricity. At minimum, the metallurgy of iron, copper and zinc (for brass) had to be in place for the for the discovery and use of electricity. The path to broadcasting and receiving radio waves required a fair degree of curiosity and industrialization.
As in the past, I will discuss some observations as a chemical scientist with cancer.
In 2013-4, I was treated for stage 4 squamous cell throat and separately, stage 4 prostate cancer and have been in remission since.
I picked up a new cancer as well as another precancer diagnosis a few weeks ago in late July, 2025. My very first colonoscopy (!!) identified several small precancerous polyps which were snipped out. The procedure was a breeze as was the much-derided colon-blow opening festivity. Propofol is amazing stuff.
Eleven days ago, I had my second partial glossectomy. The first in 2022 turned up a precancerous squamous cell lesion on the side of my tongue. The second, last week, removed a squamous cell tumor. A shallow, nickel-sized piece of tongue was removed along the middle-left edge. A skin graft from my arm was not performed, thankfully. Imagine having a hairy skin graft on your tongue!!
Prior to the surgery, I had to sanitize my arms, legs and torso with chlorhexidine (below as the gluconate), a common antiseptic. They even reamed out my nostrils with Povidone-Iodine. Incidentally Betadine is a trade name of Povidone-Iodine. First time for body-wide sanitization.
Graphic from chemical supplier TCI from Google images. This structure is the digluconate salt. Notice that the lower structure is a carboxylic acid and the chlorhexidine structure above is an is called a bibisquanide. Altogether there are 2 acid protons and 10 basic nitrogen atoms. The combination is actually an ammonium/iminium salt for water solubility.
Povidone is the polymer poly(N-vinylpyrrolidone). It is used in many medicaments and is regarded as relatively safe. The chemical structure is shown below.
Image from Wikipedia. Povidone Iodine is a broad spectrum bactericide useful against bacteria, protozoans, fungi and viruses. It is prepared by combining PVP with hydrogen iodide and iodine. It slowly releases iodine in situ.
/*begin anecdote*/
Of interest to me is the use of N-vinylpyrrolidone. In a previous life I had prepared poly-NVP by solution polymerization on many occasions as a base for experimental liquid ink charge carriers in xerographic imaging. Very simple to make. The point was to replace existing liquid inks that used flammable hydrocarbon solvents. The startup who recruited my small startup went under because the solvent they were banking on didn’t dry fast enough for their economic model. The whole thing rode on the use of low viscosity 0.5 centistoke silicon fluids.
The business plan was to provide the photocopiers at low cost and then rack in the profits on consumables- a common strategy in the printing business. The founders were all retired from the giants of the photocopier industry. They knew all about the technology except for this seemingly small ink modification.
Alas, the drying rate was far too low and the image transfer was of persistent low quality. The elderly and retired engineer behind this invention fell over dead in the middle of it. He provided the patents but never actually built a prototype or even physically investigated the suitability of silicone fluids and ink composition. It was a big handwaving exercise that the founders bought hook, line and sinker. In the end, the sinker took them to the bottom still grasping for that golden ring they so desired.
/*end anecdote*/
The ever-popular opioid fentanyl was part of the basket of anesthetics used in the partial glossectomy procedure. A little mentioned side effect of fentanyl is extreme itchiness, particularly of the face. In post-op I had this in spades and it was very uncomfortable for several hours. My interest in the chemistry of fentanyl had never fully ballooned to include side effects.
The tumor board at the university hospital I go to voted that I should undergo exploratory surgery to examine the many nearby neck lymph nodes for evidence of spread. This would point to further treatment. My throat cancer was discovered when a swollen sentinel lymph node fused to my carotid artery and decorated my neckline.
I’ll admit that a salad of pessimism and resignation with breadsticks of nihilism has arrived at my table at life’s Olive Garden. Much depends on how the upcoming lymph node surgery will come out. We’ll have to wait and see.
Assigning the stereochemical configuration of a cyclophane or a metallocene is a rare task out there for most chemists. Two classes of molecules, cyclophanes and metallocenes, have flat features that can be tough to assign priority numbers to.
I ran into an organic chemistry resource on LinkedIn that was worth zooming in on. It is a blog called MakingMolecules and it features graphics that give instruction and illustrate most aspects of sophomore organic chemistry. Having taught organic chemistry I know that nomenclature is a favorite topic among students (wink wink, nod nod), especially where stereochemical configurations are concerned. Ah …, if only the world had only chiral acyclic hydrocarbons to name. As we know, there is much, much more than that.
Finding a chiral carbon atom on most simple molecules isn’t that hard. Find a carbon atom with 4 different groups attached and then check for symmetry around it from every direction while you rotate the parts.
If it has rotational symmetry or a plane of symmetry including the atom of interest, then it may not be a chiral “center”. Molecules with a C2 symmetry axis but without a mirror plane can be chiral.
The more difficult molecules to characterize as chiral are those that have unusual rules necessary for an R or S configuration.
It is amazing what you’ll find by just looking around. While reviewing recent blood test results it occurred to me that I didn’t know the first thing about albumin as a protein. A Google word search led to numerous links but provided many images as well. The crystal structure is below.
Source. The crystal structure of human albumin. The albumin was crystallized in the presence of excess palmitic acid for x-ray analysis. Front. Immunol., 25 January 2015, Sec. Vaccines and Molecular Therapeutics Volume 5 – 2014 | https://doi.org/10.3389/fimmu.2014.00682
It is not uncommon to describe the enzyme-substrate complex as a highly specific lock and key structure. In the earlier literature is was axiomatic that enzymes are described as being highly substrate specific and use a single binding site for a given substrate. This notion is not always correct as the above graphic shows. Albumin is produced in the liver and is sort of a molecular ox cart- it can transport many substrates in the blood.
The job of human albumin is to get various substrates mobilized in the bloodstream and offer them at a desirable location. With the high molecular weight of enzymes, and the consequent low molarity available, it is astonishing that the heat of binding of substrate to enzyme can be measured at all.
One way to determine binding enthalpy and stoichiometry of a substrate to enzyme is ITC- Isothermal Titration Calorimetry. These calorimeters are available from several manufacturers such as TA Instruments and Malvern. ITC is just a type of reaction calorimeter that allows for immediate access to the reaction mixture. It is a microscale RC1 in effect. An enzyme solution can be titrated with substrate allowing for a visual determination of an equivalence point where 1 eq of enzyme active sights just matches the titrant equivalents. From such an experiment both enthalpy and stoichiometry can be measured. The image below is from TA Instruments and nicely shows the graphic output of an ITC experiment.
Source: TA Instruments product brochure. Each peak is an aliquot of titrant. Note how cleanly the signal goes to baseline between aliquots.
This graphic shows the baseline signals from titrating directly into buffer. This is subtracted from an actual run. From TA Instruments sales brochure.
Above, the background signal from the buffer represents noise in the enthalpy signal.
TA Instruments also offer equipment for so-called nano scale experiments. See below.
The TA ITC specification table. Note the minimum heat in the low volume column: 0.04 to 0.05 microJoules with a 190-microliter sample cell size.
Albumin is endowed with binding sites open to a variety of substrates. It is like a wheelbarrow or an ox cart. It can ‘carry’ numerous substrates across several categories.
The downside of such low specificity is that albumin can bind many drug compounds at the expense of dose delivery to the desired site. Doses of drugs must be adjusted to account for drug lost to blood proteins like albumin.
Some folks have all the luck. America’s Orange Jesus has been (or will be) offered a Boeing 747 to use in place of the two presidential B747s which had developed an annoying rattle and had to be taken out of service. They are presently parked at Oskar’s Jet Shop and Grill somewhere in the Pacific Northwest. In sympathy to this niggling inconvenience to #47, an old man, the royal family of Qatar has generously stepped forward and offered a super luxury B747 for the Great One for his weekly trips to his many resorts. The B747 will transfer to #47’s Presidential Library foundation where it will remain. Some are saying that it will cost a gigabuck to upgrade it as necessary.
Keeping a third B747 ready to fly at any given moment will be expensive as are the 2 presidential jets now in the shop. In the new B747, the lavatories will have to be reduced in size for the media’s discomfort. Vending machines will be added for feeding the media but will be limited to exact change only. The machines will also offer #47’s trading cards which will include a 5 % discount coupon for his golden sneakers. As always, payment can be made with #47’s cryptocurrency plus a $50 service charge.
As the authoritarian regime of #47 continues to take hold, an increasing number of governments will express fealty and line up to offer something special, which #47 will gladly take and keep, the emoluments clause notwithstanding, found in Article I, Section 9, Clause 8 of the U.S. Constitution. It has already begun to turn stomachs worldwide but others will be attracted to the new ‘democratic dictatorship’ ramrodded by the GOP and led by the Orange Jesus himself. Many people around the world tolerate authoritarian leaders or see them as admirable strongmen. Kick ass and take names, some say. But too often the names aren’t taken or made available to anyone. There is just the ass kicking and transfer to a holding facility. Habeas Corpus? Gone! Evidence of a crime? Nah. Filing an appeal? What, are you being serious?
To the many readers outside the USA, know that a very large number of US citizens are horrified and in serious opposition to #47 and his MAGA movement. However, it seems that the Founders of this country failed to anticipate a situation where a single party rules both houses of Congress, the White House, the Supreme Court, and the governors and legislative bodies of many states. The Founders assumed that the checks and balances between the three co-equal branches of government and built into the government they designed would protect the democratic republic and keep essential government services working. They could not anticipate a simmering populist movement amplified by instantaneous social media. Whereas in times before the internet and smart phones, a large number of disaffected and under-educated citizens in America now have access to media of all kinds and can gravitate towards whatever populism that appeals to them. There seems to be little in the way of concern about truthfulness.
The single party dominance of MAGA in US government means that enforcement of federal laws or procedure will be ignored. The Department of Justice has been slow to enforce checks and balances or just ignore it altogether. MAGA GOP politicians know that endorsement by #47 ensures that they will get votes from MAGA block and assure their political careers.
Roughly 30 % of the voting population will support #47 until their dying day, regardless of his behavior. Resistant to the lessons of history and logic, they are essentially lost to modern times. They are angry from seeing and hearing the hype surrounding modernity and the corrosive conspiracy theories involved. Not having a college education, they missed out on opportunities that open up by living in a college environment. All of the job descriptions and opportunities requiring college education aren’t necessarily posted off-campus and are therefore missed.
Until I entered the university, I was completely unaware of a host of career choices available. I grew up in a rural midwestern blue collar environment and was completely unaware of the various futures available. Many have glorified our rural culture, but I found it quite boring in my years from birth to 14 years. Sure, there are wide open spaces and nature. But the fifth time you wander out into a large pasture you begin to realize that solitude is nice but quite boring.
I was introduced to science and technology by watching the progress of the Apollo moon mission in the 1960s. It was thrilling but there was no one around who could hold a decent conversation about it with me. Basically, if you were a kid into science at that time in my state, you were alone. Just knowing about sciency topics wasn’t enough. It is nice and necessary to have discussions to explore ideas and ask better questions. To share in the wonder and majesty of the universe. That’s not too much to ask, isn’t it?
If you look the chart of elemental abundances in the cosmos below, you’ll notice that beyond hydrogen and helium atomic numbers, there is a steep log-scale drop in the abundances of lithium, beryllium and boron, or just ‘LiBeB’. This is followed immediately by a sharp exponential rise in the abundance of carbon, nitrogen and oxygen, etc. Beyond oxygen there is a general downward trend in elemental abundances. Well, except for iron, Fe. It is a special case related to the demise of stars. The zig-zag in the curve is explained by the Oddo-Harkins rule which postulates that even numbered atomic numbers are more abundant. I’ll leave this to the reader to explore.
Maybe 15 years back I decided to understand why each of the LiBeB elements are so scarce. And, if they are so bloody scarce, then how do they end up concentrated in ore bodies on earth? As a first-order approximation, you’d think that the explosion of stars and the resulting rapid dispersal of matter into the surrounding space would argue against the LiBeB concentrations on a planetary body like earth.
So, here is the question: Given that the cosmic abundances of lithium, beryllium and boron (LiBeB) are dramatically smaller than the succeeding light elements, how is it that “concentrated” ore bodies containing these elements exist on Earth?
Source: Wikipedia. “Oddo–Harkins rule.” Notice that the vertical axis is a log scale.
As I look at it now, the answer is bloody obvious. But when I asked the question 15 years ago, my understanding of hydrothermal activity and fluid movement through the earth’s crust was pretty slim nonexistent. But hey, my focus in college was not astronomy or geology.
The graphic below shows how elements can be grouped according to a few particular categories. It is an absolute tragedy that the Platinum Group Metals (yellow shading) are in such the low abundance. These elements are uniquely valuable in chemical and industrial applications.
An even more fundamental question is, how is it that the cosmic abundances of lithium, beryllium, and boron are so low? Answer: they can’t survive the temperature and pressure conditions in the core of a star. They are fuels and therefore too delicate.
So LiBeB nuclei are produced during cataclysmic stellar explosions by some kind of spallation process, scattering fragments of larger nuclei into space. Another theory claims that cosmic radiation is responsible for the spallation of larger nuclei leading to LiBeB fragments. Subsequent generations of star formation resulting from an accumulation of hydrogen, helium, and heavier elements can lead to a star system with a protoplanetary disc where mass is brought into closer proximity. Mutual gravitational attraction between dust, chunks and aggregations of solid phase matter not already drawn into the star begin over time to aggregate and form planetary bodies. Some of the larger bodies are heated to liquid phase by collisions. Smaller mass objects may remain in the solid phase. Planet or moon sized bodies can collide to produce another planetary body or just debris. A fluid body of sufficient mass will spontaneously alter its shape in the direction of spherical such that all of the mass is as close to the center of gravity as possible. A spherical planet is one in which all of the mass is as close to the center of gravity with minimum potential energy as possible. A flat, disk-shaped body does not. It is hard to say just exactly how a flat planet-sized body would form with only gravity to drive it.
A cooling but still partially molten planetary body will begin to sort its large-scale composition by density and melting point. High melting point materials near a cooler surface will form solid crystalline bodies within the magma and then settle and possibly stratify according to density, then re-melt and disperse and convect to repeat the process. With cooling, the magma becomes increasingly viscous which would be expected to slow down mixing within the magma body. Over a long period, the planetary surface will continue to cool by loss of radiant energy and eventually the surface will crust over. Planetary bodies will accumulate mass by gravitational attraction as they sweep through space in their orbits, adding whatever chemical diversity that may be falling inwards to the surface. It seems reasonable to suppose that infalling dusts, rocks and asteroids are not uniform in their total compositions and may result in a non-uniform, spotty distribution of elements on the planet.
Solidification
Well before the surface cools to the point where a gas such as water can condense to form bodies of liquid water, water vapor in the atmosphere can convect to produce clouds at altitude, releasing latent heat and further adding to the heat transfer from the planet. Eventually, liquid water on the surface of a cooling planet can carry heat energy upward by conduction from the surface and atmospheric convection upwards, releasing the latent heat of condensation as clouds form in the upper atmosphere where it is colder. Heat transferred to the atmosphere will radiate infrared energy in all directions including space. The planet has developed weather.
Source. GIA. Formation of minerals from magma. Minerals with the highest melting point begin to crystallize first, depleting the molten phase of those components. This is fractional crystallization described in Bowen’s Reaction Series.
Solidification processes in a magma begin to spontaneously partition or nucleate into particular combinations of elements. Some groups elements like silicates combine with metals into molecules (covalent bonds and ion pairs). For a period of time on any given crystalline surface, the temperature will support equilibration to and from the magma wherein ionic species will attach to the crystalline surface from the magma. With sufficient temperature, ions can detach from the surface and diffuse into the magma. This process will continue as the temperature drops freezing the magma and suppressing diffusion.
Bowen’s Reaction Series summarizes trends in the order of melting/freezing of various classes of minerals with temperature in magma. From location to location, the composition of magma is variable where some may be silicate rich and others silicate poor. That melting/freezing points of minerals vary with composition shouldn’t surprise my chemist friends.
Graphic: Shamelessly and laboriously redrawn by Sam Hill.
Reaction selectivity is driven by the sign and magnitude of Gibbs energy in a particular transformation and the ability of the combination process to be reversed at the local temperature. The formation of crystals or their dissolution in hydrothermal fluids or magma is taken to be a type of reaction. Many of the species present at magma temperatures will be ion pairs.
A few covalent species like the highly stable Si-O bonds in silicates are found in great abundance. The O of Si-O may or may not be connected to other silicon atoms such as … -O-Si-O-Si-O-Si-O-Si-O- … for examples. There is no upper limit to the number of O-Si groups possible in minerals, though their assembly can go many directions. Quartz is a 3-dimensional network homopolymer. All 4 of the oxygens on silicon are connected to adjacent silicon atoms via the oxygen linkages. Quartz is a mineral comprised of all covalent bonds. Quartz has a much higher softening temperature than manufactured glass.
Silicon readily forms tetrahedral connections with oxygen as in silicate (SiO4)4- units. Si-Si bonds are not found in nature.
In a hydrothermal fluid solution or in magma, ionic species randomly diffuse, collide or swap partners. Charged species like iron (2+) cations can collide but will bounce apart owing to their like positive charges. But at a sufficiently low temperature, a sulfide (2-) anion can collide with the oppositely charged iron (2+) cation and remain connected as iron sulfide. The two ions are now chemically bonded and in doing so, heat is released and dispersed into the surroundings leading to a localized increase in temperature. Heat spontaneously flows from high temperature material to lower temperature material. The localized heated surrounding crystallizing minerals can keep dispersing the energy outwards, but as it encounters more mass which also absorbs heat energy, the resulting temperature rise diminishes rapidly as the energy is diluted over more mass.
Chemical transformations have two broad drivers- kinetic and thermodynamic. Kinetically driven transformations favor the pathways that are the fastest Thermodynamic transformations are equilibrium-controlled meaning that transformations that are reversable will favor the end state having the lower Gibbs energy. The Gibbs energy (ΔG) combines the heat of reaction (enthalpy, H) minus the entropy (S) times the absolute temperature (T). The entropy accounts for whatever heat energy may be gained/lost from/to the environment. When a bond forming reaction occurs, heat is released and moves into the environment.
Mineral nucleation starts with a microscopic “seed crystal or compatible surface” that will provide a template to further crystal growth by like molecules. Some combinations of elements will begin to polymerize forming high melting point, low solubility molecules comprising silicates and aluminates.
The concentration of the Li or Be or B into what would later become economic ore bodies is driven by the flow of ground water. Subsurface hot water flow in the crust is referred to as hydrothermal flow and from it is where concentration of the LiBeB begins. An ore body is a mass or formation of rock that is enriched in some particular element or group of elements. Usually, these elements are part of chemical compounds rather than pure elements. Gold would be an exception.
Definition- Minerals and Rocks
Mineral– A solid substance with a well-defined chemical composition and characteristic crystal structure.
Water, and especially hot water under pressure, will chemically alter the rock it is in contact with. While it is in contact, some fraction of the altered rock will dissolve and some components may be entrained as suspended solids in the fluid. This will extract and partition part of the altered rock into a solution with a range of possible compositions depending on solubility, pH, temperature and pressure. In this way, elements get partitioned into solution phase and away from the solid phase.
Source: Wikipedia. This diagram shows felsic magma as the heat and mineral source. Felsic magma is enriched in the lighter elements like silicon, oxygen, aluminum, sodium and potassium. Because of the enhanced presence of silicates and aluminates, the magma or lava tends to be more viscous.
Hydrothermal solutions can sit in place for a very long time, eventually saturating with mineral components. If there is cooling in place, the saturated solution can precipitate to form a solid body of mineral filling the local spaces. The deeper the fluid, the warmer it will be and likely the slower it will cool. However, if the surrounding rock is porous or develops fractures or faults, the hydrothermal fluid will flow to the zone of lower pressure. If the flow is into a cooler zone, there may be precipitation of the least soluble components leading to solid mineral formation. Precipitation can also occur from a drop in pressure.
Solubility vs Temperature vs Pressure Example with Quartz
The effect of temperature and pressure on precipitation of silicate can be seen with the beautiful pressure/temperature/solubility relationship shown below. For instance, we can see that for temperatures at or below 150 oC, there is very little change in solubility of silicate with increasing pressure. On the higher side of the temperature scale at 350 oC, we see that there is a considerable solubility change with increasing pressure. At high pressure, say 700 MPa, the solubility of silicate is most sensitive to changing temperature.
Source: For educational purposes only. Williams, Randolph; Fagereng, Åke Fagereng, The Role of Quartz Cementation in the Seismic Cycle: A Critical Review, March 2022 Reviews of Geophysics 60(1), DOI:10.1029/2021RG000768
The research article above cites the solubility of SiO2 in mg/kg water, or ppm. I am using the term silicate indicating hydrated and charged SiO2, the SiO4 tetrahedral form, which is known to dissolve in water. It is common in some of the geological literature to refer to the neutral oxide form of a mineral or metal.
SiO2 is often observed in its amorphous or crystalline topological polymer (or network polymer) form as a quartzvein, pegmatite or crystalline mineral component of a felsic igneous rock. Quartz found in a vein is there because a fault or fracture was available for filling with a hydrothermal fluid. As the curve above infers, saturation and precipitation can be abrupt with a sudden drop in pressure during a fault movement or sudden opening of a fracture network. Quartz veins are often accompanied by metallic gold in the upper oxidized zones (gossan) of the formation. In the context of mining, these veins are sometimes called quartz reefs.
Back to LiBeB
Although LiBeB elements are scarce, there are hydrothermal processes in the crust that can concentrate them in economic quantities.
An excursion into ore geology shows that selective hydrothermal extraction and transport are critical to the formation of a great many types of ore bodies. In fact, all three elements of LiBeB are moved by hydrothermal fluid transport on Earth at some point.
Lithium
Lithium metal is quite reactive and not found on Earth in the neutral metallic state. It is a single-electron donating Group 1 element and the lightest atomic weight metal of all the elements. Lithium has a large standard reduction potential of -3.05 Volts and is an excellent donor of electrons and a poor acceptor of electrons.
Lithium metal reacts with three major components of air: water, to form LiOH + H2; Oxygen to form Li2O + Li2O2 + H2; and nitrogen gas to form NLi3, lithium nitride. While other air-reactive metals can be stored under a hydrocarbon like kerosene for protection, lithium will float in these liquids and may be mixed with a heavy hydrocarbon or grease to keep it covered.
Lithium deposits can be split into two general domains- brines/muds/leachates, and hard rock deposits. Spodumene is the common hard rock source of lithium found in a few places around the world. Spodumene is lithium aluminum inosilicate and has a few variants such as Hiddenite, Kunzite, and Triphane coming from trace elements present in the surrounding rock.
The Silicate Zoo section is a bonus feature and may be skipped.
Bonus: A Step into the Zoo of Silicates
Spodumene is an inosilicate. Silicates as a group make up 90 % of the Earth’s crust. The basic unit is the tetrahedral [SiO4]4- silicate with 4 oxygen corners of the tetrahedron. These are known as ortho- or nesosilicates. The 4 minus charges are balanced by 4 plus charges provided by one or several metal cations at a time. Orthosilicates are the simplest variants of silicates.
A basic silicate ion, (SiO4)-4 with cations omitted. Graphics by Arnold Ziffel.
The corner oxygen ions of silicate can be attached to the silicon of another silicate. These are called the sorosilicates and have the formula [Si2O7]6−.
A sorosilicate ion, (Si2O7)-6 with cations omitted. Two silicates sharing an oxygen. Graphics by Arnold Ziffel.
Silicate units can also form rings called cyclosilicates. The rings consist of silicate tetrahedrons with alternating linkages of silicon-oxygen atoms. The general formula is [SinO3n]2n−.
A cyclosilicate, (Si3O9)-6 with cations omitted. Commonly called ‘D3’ when pendant oxygen atoms are replaced by CH3. Graphics by Arnold Ziffel.
There are several varieties of inosilicates. As a group they link silicate units into interlocking chains. There can be a single chain (pyroxenes such as spodumene) or two (amphiboles such as asbestos). The single chain inosilicates have the formula [SinO3n]2n−. The double chain inosilicates have the formula [Si4nO11n]6n−.
Monomeric silicates can polymerize along 1, 2 or 3 dimensions and by 1 or 2 connections to other tetrahedral silicates through the sharing of oxygen atoms. Graphic: Libretexts.
Phyllosilicates are sheet structures of silicate and have the general formula [Si2nO5n]2n−. This group includes micas and clays.
The tectosilicates are 3-dimensional frameworks and have the general formula [AlxSiyO(2x+2y)]x−. Note that aluminum may be present. This tectosilicate group includes quartz, feldspars and zeolites.
If you look at all of the general formulas, note that the negative charges must be balanced with positive ions (cations) of some kind. They are typically metal cations that vary in positive charge and ionic radius, although they can be capped off with hydrogen. A metal cation with its positive charge and ionic radius can be most easily replaced by a different metal with the same charge and similar ionic radius. Different charges and ionic radii are possible replacements but cause distortions in the lattice structure.
Minerals can form such that a silicate [SiO4]4- unit can be replaced by one or more aluminate (AlO4)-4 units and the metal counterions can be substituted by other metals of the same charge and similar ionic radius.
Back to Lithium
A growing fraction of lithium exploration and production involves lithium brines. Subsurface brines enriched in lithium (up to 0.14 %) can be pumped to the surface and exposed to sunlight in large evaporation ponds. Brines are saline solutions comprised of numerous soluble ionic substances. The lithium component must be isolated to a specified level of purity prior to sale. The most common product leaving a lithium mining operation is the insoluble lithium carbonate.
The process of concentrating a mineral from the ore is called beneficiation. An ore is comprised of the target mineral and gangue or mine waste from previous activity. The idea is to use economical physical and chemical methods to remove the gangue from the target mineral.
The largest collection of lithium brine reservoirs, known as salars, is in the Lithium Triangle in Latin America. The countries in the Triangle are Chili, Bolivia and Argentina. This area holds more than 75 % of the world’s lithium resources under their salt flats.
The salar brine is pumped into an evaporation pond and allowed to concentrate in the sunlight for a year +/-, then it is filtered and sent to another evaporation pond for further concentration. What happens next depends on which of the several possible processes is being used. The type of processing that is used depends on few things: The composition of the ore and interfering substances present; the company may have in-house technology they can adapt; there may be patent constraints in force; the process economics will apply considerable effects on equipment size and required annual throughput.
Source: Google maps. The Yanacocha gold mine owned by Newmont. The curved features are evaporation ponds taking advantage of evaporation and subsequent concentration of the brine by solar energy. This process is fractional crystallization, precipitating the least soluble ion-pairs in the presence of more soluble ion-pairs. An ion pair is defined as XmYn, where X is a cation of variable charge and Y is an anion where m and n are numbers such that m times the cationic charge plus n times the anionic charge add to zero net charge.
Economic ore is that resource which can be beneficiated and further refined and sold at a profit. So, the amount of ore that constitutes an economic deposit can shrink or grow with the market price of the product.
A recent development in lithium resources is the Rhyolite Ridge Lithium-Boron Mining Project near the ghost town of Rhyolite, Nevada, and southwest of Tonopah. The mine will be a large scale open pit operation operated by the Australian mining company ioneer. The mining will be carried out in the conventional drill-and-blast, and load-and-haul method. In the beginning the mining fleet will use automated haul trucks.
Even though nature has provided a concentrated lithium ore body, people still have to go to considerable lengths to produce economical lithium product, all the while gambling on the market price in the future.
Beryllium
Beryllium, Be, atomic number 4, has some very useful properties that make it a valuable metal. It is also quite scarce. The world’s richest beryllium deposit is located near Spor Mountain in Utah. The mine is operated by Materion Brush Inc., formerly known as Brush Wellman. The mine is operated by Materion Inc., formerly known as Brush Wellman. The beryllium rich tuff is located by trenching and drilling. Tuff is compacted volcanic ash that has been cemented into porous rock by contact with water flows. The area also contains fluorspar and uranium, separately, in combination with beryllium. Bertrandite (Be4Si2O7(OH)2) and beryl (Be3Al2Si6O18) are the chief beryllium-bearing minerals and fluorspar is a common accessory mineral.
Spor Mountain is located in South Western Utah in basin & range country that extends across Nevada to California.
The above map is from the US Geological Survey and shows 3 extinct calderas in the immediate Spor Mountain vicinity represented in blue. It is interesting that tuff, made from pyroclastic flows and ash where particulates are later cemented together, is the rock in which beryllium is found in the area AND there are 3- count ’em 3 -calderas right nearby. Coincidence?
Source: Google Maps. The red circle shows the location of Spor Mountain beryllium mines in Utah. Closer examination of the mines shows that the mines and roads are bare of vehicles. Nearby, a parking lot with large haul trucks can be seen, but the overall location leaves the impression that excavation of the ore has paused.
Beryllium is a rare element on earth showing up in veins, pegmatites and tuff. In the cosmos its existence is thought to be due to cosmic ray spallation.
“The beryllium tuff is a favorable host for beryllium ore because 1) it is adjacent to faults and rhyolite vents where mineralizing fluids could enter the tuff, 2) it is a porous, reactive conduit for mineralizing fluids, including both hydrothermal and ground waters, and 3) it contains carbonate clasts, which reacted with fluorine-rich fluids to precipitate fluorite and beryllium.” Source: USGS, 1998
Source: USGS, 1998. A rare showing of Be ore at the surface. The white band runn9ng diagonally across the image is the ore body. Most Be mining at Spor Mountain is open pit mining.
Boron
We’ll defer to the Wikipedia to provide background information on the element boron. The main source of economic boron is borax. Borax is a type of evaporite originating from hydrothermal fluids that have flowed to the surface where subsequently the water carrier evaporated to afford dissolved and suspended solid borax, a hydrated borate. Boron the pure element is not found, it only appears as set of various borates. There are monoborates, nesoborates, inoborates, phylloborates and tektoborates. The prefixes below are applicable to silicates and other oxides as well. The older Nickel-Strunz categorization system has been used to describe the classification of complex borate anions found in minerals.
Hydrolysis of Borax to boric acid. Graphics by Arnold Ziffel.
The structures of borax and hydrated borax above have been reduced to their minimum hydration. In reality these are idealized structures not reflecting the agglomeration into larger hydrogen bonded structures. Neutral sp2 boron atoms have an empty, low-lying p-orbital which can bond to the O of O-H groups whether from water or other borates.
The actual composition of any oxy-borate including borax will depend on its thermal history and its chemical environment. Attempting to dehydrate a borate may indeed remove water, but in doing so may open up a p-orbital on boron that would allow an exchange of oxygen species, whether another borate, boric acid or just another water molecule. This is not worrisome when producing boric acid, but when one of the OH groups of boric acid is replaced with a carbon atom, then dimerization and trimerization may occur even at low temperature under vacuum to form boronic anhydrides.
When ordering an organoboronic acid, look at the specs very carefully. Sometimes the water spec may be quite broad due to adventitious dehydration. Using azeotropic removal of water will work by toluene azeotropic distillation, but you may not recognize the 1H-NMR spectrum of the toluene solution because this dehydration method may produce the dimers, trimers and oligomers from the original organoborate. In my experience, the anhydrides work very well in the Suzuki coupling.
A trial sample of an organoborate must represent what can actually be made at scale. A lab sample will have an analysis of what a skilled chemist can do under optimal conditions. If the customer wants bulk boronic acid matching the qualifying lab sample, then you may be sunk if you cannot reproduce the sample specs in the plant. Been der, done dat.
When submitting an organoboronic acid to a customer for approval, avoid sending the very best material from the R&D lab. They will spec on that sample and expect to see the same thing from a production run.
In the organic synthesis area that I have been witness to, boron showed up in our lives mostly for purposes of aryl coupling chemistry with an aryl halide, an organoboronic ester and a palladium catalyst. The nomenclature gets confusing with boron species. Borax is a borate because of the B-O-B and B-OH bonds. But KBF4, potassium tetrafluoroborate, has a boron-based anion with 4 fluorides. The -ate suffix does not always mean that oxygen is in the formula. Many anionic boron species have a net negative charge because a group like OH or F brought the negative charge to make a tetrahedral boron. Quaternary borates are often used as a weakly coordinating conjugate anions where non-interference by the anion is needed.
Source: Data table from Wikipedia. Graph by Arnold Ziffel.
Lithium, beryllium and boron are all three transported by meteoric and hydrothermal water flows. When hot, pressurized water penetrates a fault or fracture system, the fluid can interact with whatever rock it is in contact with. Over long periods of time the fluid can corrode the wall minerals of the fault.
In this scenario, water can do several things to the rock. At the atomic level, the outermost layers of a crystal lattice in the mineral may be subject to aqueous hydrolysis making metal hydroxides, MOH, and liberating the anionic X– species from the latticework. Or, the water may just pull unaltered polar species into solution where they can swap ionic partners and either remain in solution or precipitate onto the surface features of the rock. If the hydrothermal fluids are in motion upwards to cooler regions above, precipitation may occur as the fluid naturally cools and depressurizing. Over time, layers of different insoluble material can stack onto the previous layers. This can go on until the void in the rock is filled and can no longer pass fluids through the fractured formation.
Conclusion
Despite the cosmic scarcity of each of the LiBeB elements, these elements may be found on or near the surface of the Earth concentrated as minerals in an ore body. Transport and placement of enriched individual LiBeB ores derives from multiple instances of differential solubility from the source rock to the ore body. Minerals that have more water solubility than adjacent minerals will tend to be transported in aqueous flows. The transported mineral gets concentrated in this way, but so do the minerals left behind. Aqueous flows at the surface can drop out their dissolved minerals as the surface water evaporates. As the surface water concentrates and cools, a sorting process is underway driven by solubility properties.
The original salt ion pair, M+X–, may be extracted into in water and dissociated to produce M+ and X– ions in solution. Other ionic substances like N+ and Y– can switch partners in a double displacement reaction and produce MY and NX. If it turns out that NX has poorer solubility than MY, then the mixture of M+X– and N+Y– will produce a precipitate of NX, leaving much or most of M+Y– in the water. Minerals deposited from evaporation are called evaporites.
Which is more desirable from the manufacturing perspective, the precipitate or the concentrated solution? Not being a mining engineer or an economic geologist, I can only speak as a person from the fine chemical industry. The precipitation of the desired product from a complex mixture seems a bit more desirable in that it is both an isolation and purification process. Often the solids can be washed and dried in a filter dryer and bang, you have your product.
Precipitating out an undesired solid component from a mixture, pure or not, while leaving the desired product in solution with solvent and other side components from the reaction is a bit less desirable. This version is at least another step away. If the product is a solid, perhaps a scheme can be found for precipitating it as well.
Notice: As an organic chemist and not a geochemist I will be using descriptions and vocabulary that may not ordinarily be used in geology. While a geochemist might easily write a lovely article that could bring tears to the eyes of the most sour geochemist, I will stumble forward with just my trailer park chemistry background- organometallic, organic, inorganic, physical and quantum chemistry.
When you step back and view mining technology as a whole, it becomes apparent that two of the largest scale inputs in mineral refining are water and electrical energy. On Earth diesel is also required in large quantities.
A good question for those who propose mining asteroids is this: Have you solved the water and electric power requirements for unit operations? Let’s say it is solved for one mineral. How will the value be mined, transported and gently lowered to the Earth’s surface without breaking into flaming pieces on re-entry or forming a crater in a city? Is there an element or mineral that is so valuable as to justify the costs and risks to be met for a space mining mission? Is it rhodium? Gold? Diamonds? Or what?
Do the people behind the fanciful images and hype believe that they only have to dock with the asteroid and grab valuable minerals from the surface? There is a good chance that the target ore will need exploration, excavation, and possibly some kind of blasting. The target elements may well be dispersed within the host rock. This will require comminution in preparation for further processing. The ore will likely need ore dressing which is the job of removing undesired rock from the valuable ore. This lowers the quantity of ore to be processed.
The rocky bodies in the solar system have surfaces of regolith. Regolith is an unconsolidated jumble of loose rock and dust presumably overlying a solid body. Given that the regolith may well be consist of rocks and dust accreted from a distant source, merely assaying the regolith might not reveal the minerals that could be there in abundance just below the regolith. There is no way around it- core samples will be needed to properly assess the economic geology.
PGM Mining on Earth
A look at the large-scale Platinum Group Metal (PGM) production activity in South Africa is instructive. The Bushveld Igneous Complex (BIC) near Limpopo and North-West provinces contains some of the richest PGM deposits in the world. The BIC is found in the Kaapvaal craton. The BIC also extends into Zimbabwe.
The Bushveld complex is located on a ‘craton‘ which is a section of continental crust that has been stable for 400 million years or so. Over that time period some portion of crust has not been subjected to subduction or rifting as an effect of continental drift. A craton is relatively untouched by continental drift over some lengthy time interval and as a consequence the crustal rocks found in a craton may be quite old. Here, ‘old’ means rock that has not been metamorphosed recently, vented out of a volcano or eroded and stratified in a sedimentary formation within several hundred MA.
The Bushveld complex is found in the Kaapvaal craton of South Africa, extending into Zimbabwe. A consequence of this location on a very stable parcel of continental crust is that vertical transposition of rock formations, i.e., subduction activity, has not led to metamorphism or folding of strata. This stability has allowed a relatively undisturbed magma chamber to form and cool, producing layered cumulates.
The formation of cumulates is a partitioning process within the magma chamber that produces solid minerals that can float or sink within the magma. Cumulates with higher density than the magma will tend to sink, building a layer, and lower density minerals will float to the top of the chamber and form an upper layer. In this way, minerals can self-purify and stratify by fractional crystallization.
While fractional crystallization can result in enhanced purity of specific minerals, the melt from which the crystals precipitate is also changing in composition. Magma is a viscous fluid and its components can undergo anion/cation exchange to produce new minerals upon further cooling. Anions include silicate, aluminate, sulfide, hydroxide, chloride, oxide, and a whole basket of metal oxyanions like titanate, tungstate, molybdate, chromate, etc. Cations include most every metal, sometimes including the noble metals. Every metal has a set of positive oxidation states that may be subject to reduction or oxidation to afford a different oxidation state or charge.
While both anions and cations present in magma have a particular charge, their individual size is important as well. Size and charge matter most when crystals are assembling. When, for instance, a calcium-containing mineral is crystallizing, the crystal lattice is subject to collisions with the whole gamut of species in the magma. If the temperature and pressure are appropriate, calcium (+2) cations nestle into a vacancy in the lattice. This is controlled by the concentration, temperature and Gibbs energy of the placement of the cation. However, if a different cation of +2 charge and similar ionic radius happens by, that different +2 cation may find itself occupying calcium’s place in the lattice. An example would be where the Ca+2 cation was replaced by Mg+2 or Fe+2.
Mineral crystal formation is a type of equilibrium wherein lattice anions and cations at the surface of the crystal are in equilibrium with anions and cations in the melt. The rate of crystallization or dissolution is driven by several things. Substitution of a Ca+2 ion in a lattice with Mg+2 or Fe+2 ions retains the charge balance in the lattice. But if a too large or too small +2 cation attempts to sit in place of Ca+2, a mismatch occurs which may be energetically favorable, but as a result may be much more prone to removal by equilibration. The interloping cation could be of such a size that its heat of formation is small and therefore subject to replacement by equilibration. Or not. The resulting mineral could be comprised of Ca+2 cations and M+2 cations in a non-stoichiometric ratio. Or a new mineral comprising a stoichiometric ratio of both cations.
The anions in a mineral substance can be quite varied and several may exist in a mineral at the same time as in the case of anions silicate and aluminate.
The Stillwater Igneous Complex in Montana, USA; the Sudbury Basin in Canada; and the Norilsk-Talnakh deposits north of the arctic circle on the Siberian Craton.
The Stillwater Igneous Complex in south central Montana, USA. Source: Google Maps.
Image from Google Maps. The Sibanye-Stillwater K3 shaft, South Africa.
Russia is the leading producer of palladium with 40 % of the global market. Norilsk Is also known as a center of non-ferrous metallurgy as well as noble metals. Norilsk Nickel, also known as Nornickel, is a mining and smelting company. Platinum Group Metals (PGM) have been recovered as a side stream of nickel and copper mining by Norilsk Nickel.
Open pit mile near Norilsk, Russia. Norilsk was originally started as a gulag in the far north of Siberia and eventually became a mining community.
The aerospace proponents of asteroid mining should spend some time at an actual mine. Breaking rock and hauling it around is simple on Earth but consider doing this in a vacuum at near-zero gravity. Look at all of the methods of conveyance and processing in operation at a mine that works only in a gravitational field. Blasting, front-end loaders, haul trucks, conveyor belts, crushers, ball and rod mills, flotation and settling tanks, lixiviation in sulfuric acid and several shifts of staff to operate and maintain it. Don’t forget the analytical lab and chemist or the maintenance group.
Proponents will always say that with the right technology, asteroid mining could work. But in the airgap between could and will is the nagging question of why? Maybe asteroid mining is best left to our descendants in the 22nd century.
A human trip to an asteroid, which is always in orbital motion and probably rotating, to mine and return with paydirt for the investors will always be high cost. Bodies outside of the Earth-Moon system will be nearby only for a short time, depending on the orbital period of the asteroid. While our Earth is measurably overheating, the biosphere is disintegrating and political turmoil is rampant on Earth, perhaps we should focus closer to home?
Humanity must stay focused on critical housekeeping activityhere on planet A. Monetizing the outer worlds can wait.
I do believe that eventually somebody will design mining technology to solve the unique problems of mining smaller asteroid bodies with negligeable gravity. Energy dense power sources will be needed to move commercial scale machines and ore. The big problem will be the economics. What mineral is so valuable as to justify the trillion-dollar expense of finding an asteroid with suitable quantities of mineral, up front R&D costs, and beneficiation and isolation of the mineral?
Minerals dispersed in the regolith matrix will need comminution, extraction by lixiviation, floatation, isolation and packaging. Now, we can get it back to earth orbit but then what? Do we just deorbit in the usual way?
Bringing home the paydirt
Let’s say they return 1000 kg (contained) of rhodium valued at todays price of $5400/toz (toz = troy ounce). 1000 Kg contained of rhodium = 32150.7 troy ounces, so 32150.7 toz x $5400/toz = $173,613, 780. However, just the rumor of 1000 kg of new rhodium about to come on the market will drive rhodium prices down. So, $174 million sounds like a lot of money and in a sense it is. But in aerospace and heavy industry, millions are quickly consumed.
Rhodium was chosen for its general scarcity and high price. There is no reason to suppose that rhodium will be more abundant on a given asteroid than on earth so numerous asteroids may need exploration by geologists. Core samples might be needed for the economic geologists to sketch out the size and value of an ore body.
There will be a threshold price of rhodium that must me exceeded before rocket launching and asteroid digging begins. This is how mining works on earth. Until then, the celestial rhodium discovery will just keep orbiting the sun into the future.
An aspect of PGMs is that the very few mines that produce them do so in a unique geological feature on a craton. The mechanism for PGM mineralization in districts like the Bushveld Igneous Complex in South Africa took place in a magma chamber where over time the magma began to cool. Magma gets its minerals from the mantle far below and from the walls of the magma chamber. In subduction zones the subducting crust is pushed downwards causing rising temperatures.
Subducting oceanic crust is loaded with water in several forms. Many minerals are ‘hydrated’ meaning that one or more water molecules are strongly attached to the mineral. These might be called coordinated water. The oxygens are strongly attracted to a cationic feature of the mineral. Interstitial water molecules may be occupying voids in the mineral lattice. Discrete water is only weakly attached and may diffuse elsewhere. Interstitial and discrete water may evaporate readily if exposed to air or heat. At the elevated pressures and temperatures of magma at depth, the three kinds of water are hot enough to flash to steam if the pressure was released. However, as the magma rises to the surface to cooler surroundings and lower pressures, eventually the water will flash to the gas phase moving magma in the direction of lower pressure. Just below the surface the dissolved gases including CO2, steam and SO2 will expand as a gas and push magma to the surface causing a volcanic eruption.
As the magma cools, the substances with the highest melting point begin to crystallize. If the crystals that have a higher density than the magma, they will settle lower in the magma chamber and form a distinct layer. While this layer is building, other minerals will follow in a similar process. The layers of precipitated minerals are called cumulates.
The process of minerals selectively crystallizing and precipitating to the upper or lower zones of the magma chamber. The overall process is called fractional crystallization and layers called cumulates can form. In the photo below are several layers of dark chromite cumulate.
From the Bushveld Igneous Complex. Exposure of cumulate layering of dark chromite. Mining involves following the cumulate layers.
Now that I have expressed my doubts about asteroid mining, I must ask ‘Am I being a Luddite’? Maybe a little bit, but even the doubts of a Luddite can be on the mark now and then. Asteroid mining will be an adventure for a few astronauts, profitable for aerospace contractors and an entertainment spectacle for the public; however, resources seem better used on Earth for remediation of the biosphere, diplomatic solutions for the conflict of the week, lower hydrocarbon consumption and better education, especially in the area of civics.
The whole purpose of mentioning PGM geology and mining in a post titled Asteroid Mining is that we on Earth are fortunate to have concentrated mineral deposits that exist only because of unique geological processes. These processes only work in Earth’s gravitational field. The upwelling of lower density hot hydrothermal fluids. The formation of evaporites rich in borax. Lithium brines.
Take my uranium, please
The formation of cumulates in lava chambers relies on differential density driven by gravity. The ability of rain and snow runoff to mobilize gold sulfides will produce lode gold and placer deposits. The ability of oxygenated meteoric water to oxidize insoluble U4+ to soluble U6+ in sandstone formations to form concentrated roll front deposits. The ability of oxygen to switch uranium oxidation states from U4+ to produce a soluble form (U6+) that can migrate and concentrate leading to the partitioning of U6+/U4+ species. Underground formations of uranium can be dissolved in a solution of sodium bicarbonate by injection and pregnant solutions of the uranium carbonate can be brought to the surface as a solution. This solution is run through a column of ion exchange resin beads which exchange chloride ions for the uranium complex. Once loaded, the beads are washed with a special solution to remove the uranium (6+) concentrate.
Oxidation and isolation of U6+ from U4+. Graphics by Arnold Ziffel.
Our ability to mine and isolate minerals is uniquely enabled by planet earth. The ability of nature to dissolve, mobilize and concentrate minerals into ore bodies from highly dispersed placement in source rock has been positive for humanity. A great many elements are found in a dispersed condition in the continental crust. For some, there are natural processes for concentration. For others, they form secondary minerals that end up mined with the primary ore. A few like gallium, indium and bismuth are valuable but are only available as a side stream from the primary ore. Copper is an excellent example of a primary metal whose ore includes many other metals like zinc and bismuth. Copper can be electro-refined to 99.99 % purity. The slimes left behind after the electrolysis and dusts caught in ventilation systems can be enriched in useful metals and are often collected for processing.
The purpose of citing the large-scale processes in use on the home planet is not to suggest that asteroid mining must start out at large-scale. It would likely start out as a small-scale surface or underground operation with a small crew or with robotics. Only a few select minerals would be economically suitable for recovery. Platinum Group Metals are mentioned above because of their high intrinsic value and ability to exist as the native metal. If luck is with the astro-miners, the motherlode might be easily visible so later the gangue material can be chipped off. The process of trimming ore to retain the value and discard the gangue was called ore dressing. Being quite dense, the volume of PGM metal ore may be low, but the density and mass is quite high.
If a given asteroid has never been part of a larger system with magma and sufficient gravity to force stratification by density, the cumulate model may not apply. A given asteroid having never been exposed to bulk water and consequently never been subject to hydrothermal flows and weathering may not have minerals that here on Earth are known to be formed with water or partitioned as a result of hydrothermal flows. Lake and ocean sedimentary units are almost surely absent as are processes requiring aqueous migration through porous rock as in the case of uranium roll fronts.
Asteroid mining will be a totally new activity and most all of the natural geological processes on earth will have been absent. Many geological processes on earth produce economic ore bodies. These will be largely absent on an airless, dry asteroid.
One thing to consider: Most of the rock accessible at the Earth’s surface is not economic ore. The surface of the Earth brimming with carbonates, silicates and aluminates bound to a variety of ‘ordinary’ metals like calcium, magnesium, iron, sodium, potassium and a handful of other common metals. While there are important and valuable uses for these common metals, they are predominantly found dispersed in surface rock comprised of many individual minerals, or that an ore body is too small for economic recovery.
The fraction of the desired mineral in the ore can be highly variable. Depending on the market, some parts of the ore body may be economical to mine while other parts may not. This is why cores are drilled to locate the 3-dimensional extent of the ore body, estimate the potential value and minimize the expense of digging and processing uneconomical ore.
It seems reasonable to suppose that, just as much of the surface of the earth is covered with rocks made from mineral constituents of low economic value like crushed roadbed rock or sand and cement for concrete use, why should we assume that a given asteroid would be any better endowed with value than Earth’s surface? Asteroid mining will necessarily be preceded by expensive exploration. Obviously, right? But it means that considerable money and time will be spent up front finding an asteroid that is sufficiently ‘pregnant’ with valuable metal ore. Finding investors to fund exploration and mining development today is based on economic geology surveys and signed off by certified experts.
A mine is a hole in the ground with a liar standing at the top. –Attributed to Mark Twain
On Earth many mineral deposits have been located historically by surface exposures that are part of a larger ore body. The economics of isolating any one mineral or metal in the presence of the others will depend heavily on the % concentration of the target mineral, the processing methods available and the market price of the final product. A market downturn can last months, years or represent new long-term realities in demand for the product.
Lamentations on Chemistry 