Antimony, Sb, is an obscure metalloid that rarely gets much notice outside of a few highly specialized areas of technology. The element is most often found in the mineral Stibnite, Sb2S3. Antimony is a pnictogen found in Group 5 between arsenic and bismuth in the p-block of the periodic table. Crustal abundance is 0.2 to 0.5 ppm according to Wikipedia, making it several times more abundant than silver. It has many interesting properties and uses which will be left to the reader to discover. Interestingly, there is a rare allotrope of antimony that is explosive when scratched. Luckily, this is unusual.

In a May 6, 2021, article in Forbes, writer David Blackmon cites the many uses of antimony and where it occurs in greatest natural abundance. As it turns out, the US is not one of those locations where it is found in great abundance. China has the largest abundance of antimony- greater than half of the known reserves in the world, with Russia coming in second. At present, the US imports 100 % of this key strategic material. Blackmon writes-

“Antimony is a strategic critical mineral that is used in all manner of military applications, including the manufacture of armor piercing bullets, night vision goggles, infrared sensors, precision optics, laser sighting, explosive formulations, hardened lead for bullets and shrapnel, ammunition primers, tracer ammunition, nuclear weapons and production, tritium production, flares, military clothing, and communication equipment. It is the key element in the creation of tungsten steel and the hardening of lead bullets, two of its most crucial applications during WWII.“

According to Blackmon, China currently supplies 80 % of the world’s antimony and also imports ore from other nations for refining. Here is the kicker- China may soon run short of the element. Running short of antimony doesn’t just mean that prices will rise in short supply. It could also mean that China may stop exporting much of its refined antimony in favor of internal consumption to produce goods up the value chain. China tried to do this with rare earth elements already. A country rich in strategic minerals and a sophisticated manufacturing base is a country that can wield significant power over the rest of the world. In the US, antimony is considered critical to economic and national security.

The US has had only one mining district that produced significant antimony. That would be the Stibnite mine in the Stibnite Mining District near Yellow Pine, Idaho. Mining activity stopped in the mid-1990s. The district, like most of Idaho, sits atop the granite Idaho Batholith. Volcanic activity in the past forced hot water through cracks and fissures in the rock, dissolving soluble minerals, moving mineral rich hydrothermal fluids that, when cooled, precipitated as mineral veins in the granite. Antimony minerals are often associated with another Group 5 element, arsenic, in the form of minerals like realgar and orpiment.

The Stibnite mine began as a gold mine in 1938 during the Idaho gold rush. Throughout WWII, the stibnite mine produced 40 % of the antimony and tungsten needed by the US. Tungsten, or wolfram, appears as the tungstate salt with a metal cation like iron, calcium or manganese paired with a WO4 oxoanion. The hydrothermal fluid partitions minerals in a rock formation into concentrated zones through selective solubility. This process is responsible for the formation of veins in solid rock.

Oh look. I’ve driven off into the weeds again rambling on about minerals.