What is Cavansite?
Cavansite is a vivid blue hydrated vanadium silicate, best known for radiating sprays and rosettes on zeolite-rich basalt cavities.
Mineralogy and structure
The reference formula is Ca(VO)Si4O10·4H2O. Cavansite belongs to the silicates and has a orthorhombic crystal system. The intense blue colour is characteristic, but cavansite should not be confused with the similarly coloured cadvanite. Its orthorhombic framework contains hydrated vanadium silicate groups.
Colour and appearance
Typical colours include bright blue, greenish blue, blue-green. Crystal habit, lustre, transparency and matrix association are often as diagnostic as colour.
Formation and localities
Cavansite forms in or is associated with low-temperature cavities and fractures in altered basaltic rocks, commonly with zeolites. Important documented localities include Poona in India, the Silver Peak area of Nevada and other basalt-hosted zeolite localities.
Collecting and care
Cavansite is best kept as a labelled collector or reference specimen. Protect fragile crystals from impact and prolonged humidity changes. Lead-, arsenic-, chromium- and cobalt-bearing minerals should not be cut, ground or used in jewellery.
