tangeite

{{Infobox mineral | name = Tangeite | image = Tangeite.jpg | imagesize = 260px | alt = | caption = | category = Phosphate mineral | formula = CaCu(VO4)(OH) | IMAsymbol = Tg | strunz = 8.BH.35 | dana = 41.05.01.06 | system = Orthorhombic | class = Disphenoidal (222) H-M symbol: (2 2 2) | symmetry = P212121 | unit cell = a = 7.45 Å, b = 9.26 Å c = 5.91 Å; Z = 4 | color = Yellow, yellow-green, olive green, green to dark green | habit = Rarely as short prismatic crystals, commonly as fibrous to botryoidal encrustations | twinning = | cleavage = Perfect on {010}, good on {001} | fracture = | tenacity = Brittle | mohs = 3.5 | luster = Vitreous, pearly on cleavage faces | streak = Light yellow green | diaphaneity = Transparent, Translucent | gravity = 3.75 - 3.84 | density = | polish = | opticalprop = Biaxial (-) | refractive = nα = 2.010 nβ = 2.050 nγ = 2.090 | birefringence = 0.08 | pleochroism = | 2V = 83° (measured) | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = }}

Tangeite, also known as calciovolborthite, is a calcium, copper vanadate mineral with formula: CaCu(VO4)(OH). It occurs as a secondary mineral that can be found in sandstone and also in the oxidized zones of vanadium bearing deposits.