Gyrolite

phyllosilicate

Formula: NaCa16(Si23Al)O60(OH)8.14H2O phyllosilicate Formula:
Specific Gravity: 2.36 to 2.45
Hardness: 3 to 4
Streak: White
Colour: Brown, colourless, white, green
Solubility: Decomposed by acids
Environments:

Basaltic cavities

Gyrolite is a secondary mineral that occurs in amygdules in basalt. It is stable under saturated steam conditions from 120 to 200oC (Dana).

Common impurities: Fe, Mg

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