cavansite

{{Infobox mineral | name = Cavansite | category = Phyllosilicate minerals | boxwidth = | boxbgcolor = #506dc9 | boxtextcolor = #fff | image = Cavansite-121680.jpg | imagesize = 260px | caption = Cavansite on heulandite | formula = Ca(VO)Si4O10·4(H2O) | IMAsymbol=Cav | system = Orthorhombic | class = Dipyramidal (mmm) H–M Symbol: (2/m 2/m 2/m) | symmetry = Pcmn | unit cell = a = 9.792(2) Å, b = 13.644(3) Å, c = 9.629(2) Å; Z = 4 | color = Brilliant sky-blue to greenish blue | habit = Radiating acicular prismatic crystals commonly as spherulitic rosettes | twinning = | cleavage = Good on {010} | fracture = | tenacity = Brittle | mohs = 3 - 4 | luster = Vitreous, pearly | refractive = nα = 1.542(2) nβ = 1.544(2) nγ = 1.551(2) | opticalprop = Biaxial (+) | 2V = Measured: 52° | birefringence = δ = 0.009 | pleochroism = Visible: X=Z= colorless Y= blue | streak = Bluish-white | gravity = 2.25 - 2.33 | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Transparent | other = | references = }}

Cavansite, named for its chemical composition of calcium vanadium silicate, is a deep blue hydrous calcium vanadium phyllosilicate mineral, occurring as a secondary mineral in basaltic and andesitic rocks along with a variety of zeolite minerals. Its blue coloring comes from vanadium, a metal ion. Discovered in 1967 in Malheur County, Oregon, cavansite is a relatively rare mineral. It is polymorphic with the even rarer mineral, pentagonite. It is most frequently found in Pune, India, and in the Deccan Traps, a large igneous province.