Chukhrovite-(Ca)

chukhrovite-(Ca)

Images

Formula: Ca₃Ca_1.5Al₂(SO₄)F₁₃.12H₂O
Valence: Ca₃Ca_1.5Al₂(S⁶⁺O₄)F₁₃.12H₂O
Fluoride, chukhrovite group
Crystal system: Isometric
Specific gravity: 2.23 calculated
Hardness: 3½
Streak: White
Colour: Colourless, white
Luminescence: Non-fluorescent either under short-wave (254 nm) or long-wave (366 nm) UV
Environments

Hydrothermal environments

Localities

At the type locality, the Val Cavallizza mine, Cavagnano, Cuasso al Monte, Varese Province, Lombardy, Italy, chukhrovite-(Ca) is found as low temperature hydrothermal crystallisations covering the surfaces of brittle fractures crosscutting a marcasite and REE-bearing fluorite vein. Associated minerals include marcasite, gypsum, REE-bearing fluorite, galena, sphalerite and hydrated Fe oxides. Chukhrovite-(Ca) forms sharp octahedra up to 150 μm across. Crystals are translucent to transparent and colourless to white, with a white streak and a vitreous lustre (EJM 24.6.1069-1076, HOM).
Chukhrovite-(Ca) from the Val Cavallizza mine - Image

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