Scolecite

tectosilicate

stilbite

Formula: Ca(Si3Al2)O10.3H2O tectosilicate (framework silicate), zeolite group
Specific gravity: 2.24 to 2.31
Hardness: 5 to 5½
Streak: White
Colour: Colourless, white, pink, salmon, red, green
Solubility: Soluble in common acids
Environments:

Metamorphic environments
Hydrothermal environments
Basaltic cavities

Scolecite occurs in basalt, andesite, gneiss, and amphibolite, in contact metamorphic and in hydrothermal environments. It is associated with other zeolites, calcite, quartz and prehnite.

In Eritrea scolecite has been reported in weathered basalt, associated with stilbite and calcite.

Near a pegmatite at Valle Maggia, Switzerland, scolecite occurs in crevices in biotite gneiss associated with adularia, (variety of orthoclase), epidote and chlorite.

On the Isle of Mull, Scotland, UK, scolecite occurs in profusion in basaltic cavities, and is often the final product of the sequence
albitechloriteepidoteprehnite → scolecite
though in some cavities heulandite succeeds scolecite.

Common impurities: Na,K

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