Clinoptilolite

Formula:
Clinoptilolite-Ca: Ca3(Si30Al6)O72.20H2O
Clinoptilolite-K: K6(Si30Al6)O72.20H2O
Clinoptilolite-Na: Na6(Si30Al6)O72.20H2O

All are tectosilicates (framework silicates), zeolite group
Specific gravity: 2.1 to 2.2
Hardness: 3½ to 4
Streak: White
Colour: White, Reddish white, red
Environments:

Volcanic igneous environments

Clinoptilolite is most commonly formed as a devitrification product of silicic volcanic glass from tuff (consolidated pyroclastic rock). It also occurs in cavities in rhyolites, andesites, and basalts.