Cavansite

crystals of cavansite, crystals of stilbite : Wagholi, Ahmadnagar (Ahmed Nagar ; Ahmednagar), Pune District (Poonah District), Maharashtra, India — Photo: Parent Géry · CC BY-SA 3.0

Cavansite

A deep-blue calcium-vanadium phyllosilicate named for its chemistry, forming in cavities of basaltic rocks.

Intro adapted from Wikipedia (CC BY-SA).

Cavansite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca(V⁴⁺O)(Si₄O₁₀)·4H₂O.

It crystallizes in the orthorhombic crystal system (space group Pcmn).

Key properties: Mohs hardness 3.5–4; specific gravity 2.21–2.31; typically blue; white streak; Vitreous luster; refractive index 1.787; optically biaxial.

IMA symbol Cav, IMA status: approved, named in 1967.

Found in a brown tuff partly filling a fault fissure (Lake Owyhee State Park, Oregon, USA); in a vesicular basalt and red tuff breccia, as cavity fillings and in calcite veinlets (Chapman quarry, Oregon, USA).

It is found associated with Pentagonite, calcite, heulandite, stilbite, analcime, apophyllite, thomsonite, copper (Oregon, USA); stilbite, calcite, heulandite, mordenite.

The name refers to CAlcium, VANadium, and SIlicon in the composition.

Collections: Collector Favorites, Rare & Remarkable.