The Probert Encyclopaedia of Rocks & Minerals

FLUORITE

Fluorite (calcium fluoride) or fluorspar or Derbyshire-Spar is a mineral occurring in many different colours, found in veins where it's the main mineral or with metallic ores, especially lead and silver. It generally occurs massive, but crystallizes in simple forms of the monometric system: the cube, octahedron, dodecahedron, etc, and in combinations of the cube and octahedron. It is common in dolomites and limestone and is associated with many different minerals. From the general prevalence of a blue tint in the Derbyshire specimens it is there known as Blue-John. It is often beautifully banded, especially when in nodules, which are much prized for the manufacture of vases, and it is made into a great variety of articles, chiefly ornamental. It is used chiefly as a flux in the making of steel, and also for enamelling, and in the preparation of hydrofluoric acid. It is a fluoride of calcium with the formulae CaF2 and a relative hardness of 4.
Research Fluorite