Glushinskite
Natural magnesium oxalate — an organic-mineral product commonly found where lichens grow on serpentinite.
Intro adapted from Wikipedia (CC BY-SA).
Glushinskite is an IMA-recognized mineral species in the organic mineral class, with the chemical formula Mg(C₂O₄)·2H₂O.
It crystallizes in the monoclinic crystal system (space group C2/c). It is a member of the Humboldtine, Oxalate structural group.
Key properties: Mohs hardness 2; specific gravity 1.85; Subadamantine luster; optically biaxial.
IMA symbol Gsk, IMA status: approved, named in 1960.
Occurs as veinlets in brown coal seams impregnated with natural acetic acid (Chai-Tumus deposit, Russia); formed by reaction between Mg-rich minerals and oxalic acid secreted by incrusting lichen, Lecanora atra (Mill of Johnston.
It is found associated with Whewellite, weddellite, calcite, dolomite, stepanovite, zhemchuzhnikovite (Chai-Tumus deposit, Russia); whewellite, chrysotile, quartz (Mill of Johnston.
The mineral was named to honor Petr Ivanovich Glushinskii (1908–), coal geologist, Institute of Arctic and Antarctic Geology, St. Petersburg, Russia.