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Fluorite Mineral Facts:

Chemical Formula: CaF₂  The Mineral is 48.9% Fluorine by weight.

Colors: Shades of Purple, green, yellow, blue. Color widely various most commonly light green, yellow, bluish green or purple, also colorless, white, rose, blue, brown. A single crystal may show varying bands of color; the massive variety is also often banded in color.

Hardness: 4

Density: 3.18

Cleavage: {111} perfect cleavage parallel to the cubic faces.

Crystallography: Isometric: Hexoctahedral
The crystal habit is cubic often with twinned interpenetration cubes, or cubes modified on the corners by the octahedrons. Other forms are rare, but examples of the tetrahexahedron and hexoctahedron are characteristic.

Luster:. Transparent to subtranslucent. Vitreous luster.

Optics: (Refractive Index):  1.433

An Aggregate of Fluorite Crystals

Composition, Structure and Associated Minerals:
Fluorite, or fluorspar, is the principal source of fluorine. It is usually a transparent mineral that is characterized by its fine color and its handsome crystals. Perhaps there is no other mineral known that can approach it in the beauty of its crystal groups. It also may be massive, granular or fibrous. In nature fluorite has been apparently produced both by crystallization from solutions and by pneumatolytic processes. Since fluorite is soluble in alkaline waters, its place in the rocks is often occupied by calcite, quartz or other minerals that pseudomorph it. The mineral is a nonconductor of electricity.

The color of the brightly tinted varieties is caused by extra or missing electrons in the crystal lattice, sometimes known as "electron holes". The bluish green varieties often show fluorescence (green by transmitted light, blue by reflected light). Some varieties phosphoresce when heated, giving off variously colored lights which are independent of the actual color of the specimen. Both of these effects are due to coloring electron excitation.

Identification and Diagnostics
Fluorite is easily distinguished by its cleavage and hardness from most other minerals. It is also characterized by the possession of fluorine for which it gives clear reactions. Gives a reddish flame (presence of calcium). Identification is usually by its cubic crystals and octahedral cleavage, also vitreous luster and usually fine coloring, and by the fact that it can be scratched with a knife.

Occurrence, Localities and Origins:
Fluorite is a common and widely distributed mineral. Usually found either in veins in which it is the chief mineral or as a gangue mineral with metallic ores, especially those of lead and tin. Common in beds with dolomites and limestone and has been observed also as a minor accessory mineral in various igneous rocks. It is the gangue of the lead veins of northern England and elsewhere. Associated with many different minerals, as calcite, dolomite, gypsum, celestite, barite, quartz, galena, sphalerite, cassiterite, topaz, tourmaline, apatite.

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