Afwillite
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Afwillite is a calcium hydroxide nesosilicate mineral with formula Ca32·2H2O. It occurs as glassy, colorless to white prismatic monoclinic crystals. Its Mohs scale hardness is between 3 and 4. It occu
Afwillite from Crestmore Quarry, Riverside County, California
Thaumasite
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Thaumasite is a calcium silicate mineral, containing Si atoms in unusual octahedral configuration, with chemical formula Ca3Si6·12H2O, also sometimes more simply written as CaSiO3·CaCO3·CaSO4·15H2O.
Afwillite
…is between 3 and 4. It occurs as an alteration mineral in contact metamorphism of limestone. It occurs in association with apophyllite, natrolite, thaumasite, merwinite, spurrite, gehlenite, ettringite, portlandite, hillebrandite, foshagite, brucite and calcite. It was first described in 1925 for an occurrence…
Thaumasite (white) with prehnite (green) from Fairfax Quarry, Virginia
Group of thaumasite prisms from the Kuruman, Kalahari manganese fields, Northern Cape Province, South Africa (size: 4.2 × 3.1 × 1.2 cm)