Fluorspar and Its Uses

FLUORSPAR, a little known non-metallic mineral, referred to technically as fluorite, chemically as calcium fluoride, is a compound of calcium and fluorine in the ratio of one molecule of calcium to two of fluorine. By weight it is composed of 51.3 per cent of calcium and 48.7 per cent of fluorine. Its specific gravity is 3.2. It is brittle, has a hardness of four and can be easily scratched with a knife. It weighs about 200 Ib. per cubic foot and has a melting point of 1650" F. The color of fluorspar ranges from pure white and opaque white, according to its purity, to various hues of yellow, green, pink, lavender, blue and brown, to bluish black. Although the lumps have color, when ground the fluorspar becomes pure white. The reason for this is because the mineral usually carries no fixed pigment, the color being produced by the re- fraction of light rays within the crystal structure and small quantities of organic matter which readily oxidizes. It crystallizes in the isometric system with perfect octahedral cleavages.