Hundreds of brown microcrystal aggregates of the extremely rare Hg mineral poyarkovite from Chihuahua, Mexico, on a pale matrix. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Poyarkovite
Poyarkovite is an IMA-recognized mineral species in the halide class, with the chemical formula Hg₃OCl.
It crystallizes in the monoclinic crystal system (space group C2/c).
Key properties: Mohs hardness 2–2.5; specific gravity 9.56; Red streak; Vitreous to adamantine luster.
IMA symbol Poy, IMA status: approved, named in 1980.
Found as a secondary mineral in the oxidized zone of mercury deposits.
It is found associated with Eglestonite, calomel, terlinguaite, montroydite, kuznetsovite, shakhovite, chursinite, corderoite, mercury, cinnabar, livingstonite.
The mineral was named to honor Vladimir Erastovich Poyarkov (1907-1975), Institute of Mineral Resources, Alma- Ata, Kyrgyzstan, investigator of mercury deposits.