Cavansite

Ca(VO)Si₄O₁₀.4H₂O

Cavansite is a silicate mineral that contains vanadium. It's compsition is Ca(VO)Si₄O₁₀.4H₂O. This sample is from Poona, India and is described as cavansite with stilbite and calcite. It is about 20 cm across.

Until deep blue crystal clusters like these were discovered near Poona, India in the 1970s, the only cavansite specimens known were tiny, pale crystals from Oregon's lava flows. The Poona area of India remains the sole source for such impressive cavansite. The sample is on display at the Smithsonian Museum of Natural History.

Mindat: Cavansite