Gyrolite

gyrolite

tobermorite

apophyllite

okenite

Formula: NaCa₁₆(Si₂₃Al)O₆₀(OH)₈.14H₂O

Phyllosilicate (sheet silicate) gyrolite group
Crystal System: Triclinic
Specific Gravity: 2.45 to 2.51 measured, 2.74 calculated
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 200^oC (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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