Vaterite

vaterite

larnite

tobermorite

hydrogarnet

Images

Formula: Ca(CO3)
Anhydrous normal carbonate, hexagonal paramorph of orthorhombic aragonite and trigonal calcite, forms a series with bastnäsite
Specific gravity: 2.645
Hardness: 3
Streak: White
Colour: Colourless
Environments

Metamorphic environments
Hydrothermal environments

Vaterite is a rare form of CaCO3 that is metastable below about 400°C. Dry crystals are stable in air but convert to calcite when heated to about 440°C. Converts to aragonite or calcite when boiled in water. Converts to calcite when boiled in NaCl solution (Mindat). It is a major constituent of a carbonated calcium silicate hydrogel complex formed from larnite (Webmin).

Localities

At Ballycraigy, Larne, County Antrim, Northern Ireland, UK, vaterite is a major constituent of a carbonated calcium silicate hydrogel complex formed from larnite (HOM) and also as paramorphs after larnite (Dana).

At the Hatrurim Formation, Tamar Regional Council, Southern District, Israel, vaterite is a rock-forming mineral formed at low temperatures by hydration of metamorphic calc-silicate rocks in the presence of atmospheric carbon dioxide, in slightly metamorphosed marl and conglomerate, and in weathering crusts. Associated minerals include calcite, aragonite, tobermorite, hydrogarnet and kaolinite (HOM).

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