fluorite (fluorspar, Blue John) Mineral, CaF₂;sp. gr. 3.2; hardness 4; cubic; often yellow, green, blue, or purple, but can be colourless, pink, red, or black, and often colour banded; white streak; vitreous lustre; crystals often cubes, but can be octahedra and rhombdodecahedra, and a mixture of forms; cleavage perfect {111}; widely distributed in mineral veins alone or as a gangue mineral with metallic ores, and in association with quartz, barite, calcite, galena, cassiterite, sphalerite, and many other minerals; soluble in sulphuric acid with the evolution of hydrogen sulphide. It is used extensively as a flux in the smelting of iron, in the ceramic industry, and in the chemical industry. The deep-purple, banded variety, Blue John, is used as an ornamental stone.

fluo·rite / ˈfloŏrˌīt; flôr-/ • n. a mineral consisting of calcium fluoride that typically occurs as cubic crystals, colorless when pure but often colored by impurities.

fluorite (fluorspar) Mineral, calcium fluoride (CaF₂). It has cubic system crystals with granular and fibrous masses. Brittle and glassy, it can be yellow, purple or green. It is used as a flux in steel production and in ceramics and chemical industries. Hardness 4; r.d. 3.1.