What is Wairakite?
Wairakite is a calcium-rich zeolite related to analcime, recognised in hydrothermal systems and valued for its soft pale crystals and geological setting.
Mineralogy and structure
Reference formula: CaAl2Si4O12·2H2O. Wairakite is monoclinic and commonly contains small sodium substitutions and variable water. COD 9005600 is a natural structural reference with the zeolite framework preserved. Wairakite is classified with silicates and has monoclinic crystal symmetry. Typical hardness is 4.5–5 on the Mohs scale and specific gravity is approximately 2.2–2.4.
Colour, lustre and habit
Typical colours include colourless, white, cream, grey, pinkish. The usual prismatic, granular, massive habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Wairakite forms in or is associated with geothermal fields, hydrothermal veins, altered volcanic rocks and low-temperature cavities. Important documented localities include New Zealand, Japan, Iceland, Italy, the United States and Indonesia.
A pale zeolite shaped by hot water
Wairakite sells as a geological story: its pale crystals record the movement of hydrothermal fluids through volcanic rock and geothermal systems.
Collecting and care
Protect from abrasion, acids and prolonged soaking; clean gently and keep the hydrothermal association documented.
