fluorite

{{Infobox mineral | name = Fluorite | category = Halide mineral | boxwidth = | boxbgcolor =#305c3c | boxtextcolor = #fff | image = 3192M-fluorite1.jpg | imagesize = 260px | caption = Deep green isolated fluorite crystal resembling a truncated octahedron, set upon a micaceous matrix, from Erongo Mountain, Erongo Region, Namibia (overall size: 50 mm × 27 mm, crystal size: 19 mm wide, 30 g) | formula = CaF2 | IMAsymbol = Flr | molweight = | strunz = 3.AB.25 | system = Isometric | class = Hexoctahedral (mm) H–M symbol: (4/m 2/m) (cF12) | symmetry = Fmm (No. 225) | unit cell = a = 5.4626 Å; Z = 4 | color = Colorless, although samples are often deeply colored owing to impurities; Purple, lilac, golden-yellow, green, blue, pink, champagne, brown. | habit = Well-formed coarse sized crystals; also nodular, botryoidal, rarely columnar or fibrous; granular, massive | twinning = Common on {111}, interpenetrant, flattened | cleavage = Octahedral, perfect on {111}, parting on {011} | fracture = Subconchoidal to uneven | tenacity = Brittle | mohs = 4 (defining mineral) | luster = Vitreous | refractive = 1.433–1.448 | opticalprop = Isotropic; weak anomalous anisotropism; moderate relief | birefringence = | pleochroism = | streak = White | gravity = 3.175–3.184; to 3.56 if high in rare-earth elements | melt = | fusibility = 3 | diagnostic = | solubility = slightly water soluble and in hot hydrochloric acid | diaphaneity = Transparent to translucent | other = May be fluorescent, phosphorescent, thermoluminescent, and/or triboluminescent | references= }}

Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon.