Gilalite

tectosilicate

garnet

Formula: Cu5Si6O17.7H2O
Tectosilicate (framework silicate) There are indications that a sharp loss of water occurs at about 92oC (AM 65.1065).
Specific gravity: 2.82
Hardness: 2
Streak: Light green
Colour: Green to blue-green
Environments:

Metamorphic environments

Gilalite is a retrograde metamorphic or mesogene mineral formed at the expense of a prograde calc-silicate and sulphide assemblage, commonly encrusting fractures in garnet-diopside skarn. It is also found filling cracks or interstices in diopside grains. At the type locality, The Christmas mine, Arizona, USA, it is associated with kinoite, apachite, stringhamite, junitoite, clinohedrite, xonotlite, diopside, apophyllite, calcite and tobermorite (HOM).

Common impurities: Mn,Mg,Ca

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