Parapierrotite on Realgar


Pretty cool black Parapierrotite crystals on red Realgar from its TL, the Allchar deposit, in Ržanovo, North Macedonia


Parapierrotite has a hardness of 2½ – 3 and a specific gravity of 5.07. It was named for close relation to pierrotite, which was named after Roland Pierrot, a French mineralogist. He was the Head of the Mineralogy Department and General Secretary of the National Geographical Service at BRGM.

It’s been found in 13 localities worldwide with the nearest to Colorado so far being the Lookout Pass Thallium prospect in Tooele County, Utah, often near hydrothermal deposits, associated with Chert, Weissbergite, Kermesite, Realgar, Arseniosiderite, Avicennite, Quartz, Stibiconite, and Hematite. The Allchar deposit is the only location where it seems any commercial mining took place.

WebMineral analyzed a specimen and found it contains roughly 52% Antimony, 25% Sulfur, 20% Thallium, and 4% Arsenic, so it’s quite the rock! Element collectors should be safe with this, and all other kinds of collectors should reconsider bringing home this one! Even on Mindat it says, “contains thallium – always wash hands after handling. Avoid inhaling dust when handling or breaking. Never lick or ingest.” And on top of that, the Antimony and Arsenic aren’t much safer!

Worldwide production of thallium is on the order of roughly ten tonnes annually as it doesn’t seem to be very valuable or useful, and the same goes for Antimony and Arsenic, so if you find a rock like this out on a hike, it might be best to leave it where you found it. But, be sure to take and share photos and make a new discovery!


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