fluorapatite fluorapatite fluorapatite, often with the alternate spelling of fluoroapatite, is a phosphate mineral with the formula ca5(po4)3f (calcium fluorophosphate). fluorapatite is a hard crystalline solid. although samples can have various color (green, brown, blue, yellow, violet, or colorless), the pure mineral is colorless, as expected for a material lacking transition metals. along with hydroxylapatite, it can be a component of tooth enamel, but for industrial use both minerals are mined in the form of phosphate rock, whose usual mineral composition is primarily fluorapatite but often with significant amounts of the other. fluorapatitegeneralcategoryphosphate mineral apatite groupformula(repeating unit)ca5(po4)3fima symbolfapstrunz classification8.bn.05crystal systemhexagonalcrystal classdipyramidal (6/m) h-m symbol: (6/m)space groupp63/midentificationcolorsea-green, violet, purple, blue, pink, yellow, brown, white, colorless, may be zonedcrystal habitmassive to prismatic crystallinetwinningcontact twins rarecleavageindistinctfracturebrittle to conchoidalmohs scale hardness5lustervitreous, resinous to dullstreakwhitediaphaneitytransparent to opaquespecific gravity3.1 to 3.2optical propertiesuniaxial (-)refractive indexnω = 1.631 - 1.650 nε = 1.633 - 1.646birefringenceδ = 0.002ultraviolet fluorescencefluorescent and phosphorescent.