Gyrolite

gyrolite

tobermorite

apophyllite

okenite

Formula: NaCa16(Si23Al)O60(OH)8.14H2O

Phyllosilicate (sheet silicate) gyrolite group
Specific Gravity: 2.36 to 2.45
Hardness: 3 to 4
Streak: White
Colour: Brown, colourless, white, green
Solubility: Decomposed by acids
Common impurities: Fe, Mg
Environments:

Pegmatites
Basaltic cavities

Gyrolite is a secondary mineral that occurs in amygdules in hydrothermally altered basalt and basalt tuff (Dana, Mindat). It has also been found in a pegmatite dike intruding limestone (Webmin). It is stable under saturated steam conditions from 120 to 200oC (Dana).
Associated minerals include apophyllite, stilbite, laumontite, thomsonite, okenite, tobermorite, xonotlite and calcite (HOM).

Localities

The type locality is The Storr, Portree, Trotternish, Isle of Skye, Highland, Scotland, UK.

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