Small brown crystals of pokrovskite associated to greeenish platy crystals of sjögrenite. Pokrovskite is a very rare mineral only known from a few localities worldwide. From: Huber Quarry, Upper Bavaria, Bavaria, Germany. — Photo: David Hospital · CC BY-SA 4.0
Pokrovskite
Pokrovskite is an IMA-recognized mineral species in the carbonate class, with the chemical formula Mg₂(CO₃)(OH)₂.
It crystallizes in the monoclinic crystal system (space group P2_1/a). It is a member of the Malachite structural group.
Key properties: Mohs hardness 3; specific gravity 2.51–2.52; White streak; Dull luster; optically biaxial.
IMA symbol Pkr, IMA status: approved, named in 1982.
An uncommon species in ultramafic bodies of dunite or serpentinite.
It is found associated with Dolomite, magnesite, sjögrenite (Zlatogorsk intrusion, Kazakhstan); coalingite, mcguinnessite (Cedar Hill quarry, Pennsylvania, USA).
The mineral was named to honor Pavel Vladimirovich Pokrovskii (1912–1979), Russian mineralogist, Institute of Geology and Geochemistry, Sverdlovsk, Russia.