What is Scolecite?
Scolecite is a delicate calcium zeolite, recognised by white radiating sprays and silky needle-like crystals in volcanic cavities.
Mineralogy and crystal structure
Reference formula: CaAl2Si3O10·3H2O. Scolecite is monoclinic and belongs to the natrolite group. It commonly forms sprays rather than robust isolated crystals, so the existing COD-backed structure is retained while the guide copy is refreshed. Scolecite is classified with silicates and has a monoclinic crystal system. Typical hardness is 5–5.5 on the Mohs scale and specific gravity is approximately 2.2–2.3.
Colour, lustre and habit
Typical colours include white, colourless, pink, yellow. The usual acicular, radiating, fibrous habit and vitreous, pearly, silky lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Scolecite forms in or is associated with basalt cavities, vesicles and low-temperature hydrothermal environments. Important documented localities include India, Iceland, Scotland, Switzerland, Canada and the United States.
A white spray from a volcanic cavity
Scolecite is a strong display mineral because fine needles create a soft architectural spray. Its value depends on intact radiating form, contrast with the matrix and locality.
Collecting and care
Keep dry and protected from impact. Avoid ultrasonic cleaning, acids and loose storage with harder specimens.
