Fluorite
Gemstone
Fluorite 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.
The Mohs scale of mineral hardness, based... Wikipedia
Chemical formula: CaF₂
Hardness (Mohs hardness scale): ≥ 4
Luster: Vitreous
Refractive index: ≥ 0.434
Cleavage: Octahedral, perfect on, parting on
Crystal habit: Well-formed coarse sized crystals; also nodular, botryoidal, rarely columnar or fibrous; granular, massive