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The name of fluorite, or fluorspar, comes from the fluor element, which is one of its components, associated to calcium. It was first using as a melt in steel industry and also for the making of fluorhydric acid. Fluorite has a hardness of 4 on Mohs? scale (anyway it is a standard reference between calcite, hardness of 3, and apatite, hardness of 5) and so, because of its brittleness, is no used in jewelry. Furthermore, this stone doesn?t resist to the concentrated sulfuric acid, presents a perfect octahedral cleavage, can be easily broken and finally changes color with temperature.
But fluorite has nevertheless some important gemological interest. As a fact of matter, fluorite shows a great variety of color (pink, green, blue, yellow, violet, colorless, etc?) and can even be bi or tri-color (the crystal showing blue, violet and purple curved bands is known as the Blue-John or Derbyshire spar variety and is found in England). It also presents different kinds of inclusions like 2 or 3-phasis, color zoning, fingerprints, tensions, cracks, etc? For these reasons, much confusion is possible with several stones like emerald and amethyst, for example.
The crystal habit is usually a cube, rarely octahedra or dodecahedra, and most often free of host-rocks. Fluorite is one of the favorite for minerals collectors due to its beautiful shapes and colors.
Fluorite is a calcium fluoride (CaF2), i.e. it is a halogen crystallizing in the cubic system. For this reason, optical properties are the same in all direction. It is so a single refractive stone and doesn?t show any pleochroism. Its specific gravity is about 3,18 and it usually shows fluorescence. Fluorite occurs in magmatic rocks, metallic mines, and also in sedimentary rocks. In addition to Thabeikyin which is a few kilometers on the west of the Mogok valley and produces blue-green stones of quality, fluorite is mined in many places world wide as France (Alpes), Mexique, United-States (Illinois, New Hampshire, Missouri), Canada (Ontario), England, Germany (Saxony, Bavaria, Baden), Czechoslovakia (Bohemia), Nigeria, and also in Italy and Norway.
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