Stishovite

oxide

quartz

Formula: SiO2 simple oxide, rutile group
Stishovite is an ultra-high pressure polymorph of quartz Silica minerals stability diagram
Specific gravity: 4.28 to 4.35
Hardness: 7¾ to 8
Colour: Colourless
Solubility: Insoluble in common acids and only very slowly soluble in HF
Environments:

Impact zone of a meteorite

Stishovite formed from quartz through high transient shock pressure and high temperature, in the impact craters of large meteorites, where it is found as microscopic grains. Also in ultra-high pressure rocks.

Alteration

Stishovite is a very high pressure polymorph of quartz. With increasing pressure, coesite alters to stishovite at about 90 kbar, and at about 2,770oC and 110 kbar pressure, coesite, stishovite and the silica melt are in equilibrium.

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