Glushinskite

glushinskite

whewellite

stepanovite

zhemchuzhnikovite

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Formula: Mg(C2O4).2H2O
Oxalate, humboldtine group
Specific gravity: 1.85
Hardness: 2
Streak: White
Colour: White, colourless
Solubility: Soluble in water, easily dissolved by hydrochloric acid
Environments

Biogenic

Glushinskite is a common biomineral formed by reaction between magnesium-rich minerals and oxalic acid secreted by incrusting lichen (Webmin).

Localities

At the Lake Huleh Preserve, Northern Jordan Valley, Northern District, Israel, glushinskite occurs in desert plants.
The saguaro is a cactus that grows to 15 m tall and weighs up to several tons, of which 85% to 90% of the mass is water. Roughly 18% of the dry mass consists of the biomineral weddellite, derived from atmospheric carbon dioxide by photosynthesis. After the death of the saguaro, minerals crystallise in the rotting flesh, formed from elements released from the decay of the cactus by microorganisms.
During the initial stages of decay, minerals formed include lansfordite, nesquehonite, glushinskite, monohydrocalcite, calcite and vaterite. Further decay produces warm, moist pockets within the dead saguaro that contain abundant, glassy lansfordite crystals to 1 mm in diameter. Then nesquehonite and monohydrocalcite crystallise and finally a pale-brown to tan-coloured sand of weddellite and its transformation product monohydrocalcite. This monohydrocalcite further alters to calcite. Decay of the saguaro adds atmospheric carbon to the soil as inorganic carbon from the transformation of the biomineral weddellite to calcite (AM 88.1879-1888).

At Mill of Johnston, Insch, Aberdeenshire, Scotland, UK, glushinskite occurs at the lichen/rock interface on serpentinite colonised by the lichen Lecanora atra. It is formed by reaction between magnesium-rich minerals and oxalic acid secreted by the incrusting lichen, and found in a creamy white layer intermingled with the filaments of the lichen fungus. The glushinskite consists of crystals 2 to 5 microns in size with a distorted pyramidal shape, often with curved and striated faces. Associated minerals include whewellite, chrysotile and quartz (AM 66.439, HOM).

At the type locality, the Chai-Tumus coal deposits, Lena River Basin, Bulun District, Polar Yakutia, Sakha Republic, Russia, glushinskite occurs as veinlets in brown coal seams impregnated with natural acetic acid. Associated minerals include whewellite, weddellite, calcite, dolomite, stepanovite and zhemchuzhnikovite (HOM).

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