Fluorite, or Fluorspar, a mineral that is the chief commercial source of fluorine. Fluorite occurs mainly in transparent or translucent crystals. These are sometimes colorless but much more often blue, violet, purple, red, yellow, brown, green, or other colors. Some varieties are fluorescent.

Fluorite is used mainly in the manufacture of hydrofluoric acid. It is also used as a flux in making steel, iron castings, and iron alloys, and in melting and casting aluminum and magnesium. The mineral is also used in making opal and flint glasses, and in enamels to coat cast iron and steel. Some colored varieties are used as gems or are carved into vases or other ornamental objects.