basaltic cavities

Formula: NaCa2Si3O8(OH)
Inosilicate (chain silicate), wollastonite group

Specific gravity: 2.8 to 2.9
Hardness: 4½ to 5
Streak: White
Colour: White, grey, sometimes greenish, yellowish, colourless
Solubility: Slightly soluble in hydrochloric acid

Plutonic igneous environments
Basaltic cavities

Pectolite is a secondary mineral similar in occurrence to zeolites. It is found lining cavities in basalt, associated with zeolites, prehnite and calcite.

At the Clee Hill quarry, Titterstone Clee Hill, Shropshire, England, UK, pectolite has been found on dolerite (RES p296).

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