Wairakite

Formula: CaAl₂Si₄O₁₂.2H₂O

Origin of name: locality Wairakei, North Island, New Zealand

Crystal system: Monoclinic

Crystal class: 2/m

Twinning: common on {110}, lamellar

Unit cell: a = 13.69 Å, b = 13.68 Å, c = 13.56 Å, b = 90.5°

Colour: Colourless to white

Diaphaneity: Transparent to translucent

Luster: Vitreous to dull

Habit: Crystals subhedral, may show octahedral-like faces, to 15 mm

Hardness: 5.5 to 6

Specific gravity: 2.26

Cleavage: 1; {100} distinct

Tenacity: Brittle

Streak: White

Synonyms/varieties:

Comments: member of the zeolite group