Galkhaite Locality: Getchell Mine , Adam Peak, Potosi District, Humboldt County, Nevada , USA ( Locality at mindat.org ) Size: 4.2 x 4.1 x 1.8 cm. A SUPERB miniature of lustrous, gemmy to opaque, dark blood-red galkhaite crystals to 3 mm RICHLY scattered on matrix from the famous Getchell Mine of Nevada from small finds in the late 1970s stashed until recent years by the mine geologist. Galkhaite is a ULTRA-RARE cesium, thallium, mercury sulfosalt and this is an OUTSTANDING example. SELDOM do you see galkhaite specimens with this many gemmy crystals! — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Galkhaite
A chemically complex thallium-caesium sulfosalt — the only natural phase combining caesium with mercury and arsenic.
Intro adapted from Wikipedia (CC BY-SA).
Galkhaite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula (Hg₅Cu)CsAs₄S₁₂.
It crystallizes in the cubic crystal system (space group I-43m).
Key properties: Mohs hardness 3; specific gravity 5.4; Yellow-orange streak; Vitreous to adamantine. R: (400) 30.5, (420) 29.7, (440) 29.3, (460) 28.8, (480) 28.0, (500) 26.8, (520) 26.6 luster.
IMA symbol Gkh, IMA status: approved, named in 1971.
Found in hydrothermal Hg–Au deposits.
It is found associated with Pyrite, stibnite, cinnabar, metacinnabar, aktashite, enargite, wakabayashilite, orpiment, realgar, getchellite, calcite, fluorite, quartz (Russia); pyrite.
The name refers to the Gal-Khaya deposit, Russia.