Cubic fluorite crystals, close-up. Also known as fluorspar, this mineral is composed of calcium fluoride (CaF2). This is a cubic, or isometric, mineral, though octahedral and more complex isometric forms also occur. Fluorite is used in the making of opalescent glass, enamels, cooking utensils, hydrofluoric acid, and as a flux material in the smelting of iron. The mineral gave its name to the property fluorescence, as impurities cause many samples to fluoresce strongly in UV (ultra-violet) light.