Realgar, Getchell Mine, Nevada
Mineral Matters #470
Whilst (re) going through some of the minerals that I got from Charles Willett, I came across this aesthetic specimen. Another one that included some species not listed on the label, and therefore another example of my Hidden Collection.
The label mentions realgar (red), stibnite (silver prismatic) and orpiment (orange). But there are three other species present: tiny pale yellow-green sulphur crystals, colourless quartz crystals, and an unidentified metallic sulphide. There are many. Unfortunately, it is not crystallised and is likely to be a common sulphide, so it will remain unidentified.
The Getchell Mine, located in the Potosi Mining District of Humboldt County, Nevada, is renowned for its rich deposits of arsenic sulphide minerals. Discovered in 1933 by prospectors Edward Knight and Emmet Chase, the mine began production in 1938 with financial backing from Noble Getchell and George Wingfield. The Getchell Mine is particularly famous for the mineral getchellite, a rare sulphide of arsenic and antimony, formula AsSbS3, which was first identified at this location, bright red realgar, formula As4S4, and dark red galkhaite, formula (Hg5Cu)CsAs4S12.
The realgar is light sensitive and specimens need to be kept in the dark as much as possible to avoid changing to pararealgar.
Below: Realgar, stibnite, orpiment, sulphur and quartz, Getchell Mine, Adam Peak, Potosi Mining District, Osgood Mountains, Humboldt County, Nevada. Width of view 6mm. Click on the image for a higher resolution version.
