Fluorite Specimens for Collectors
Fluorite is interesting to mineral collectors because it has has several different crystal habits that produce well formed clean crystals. The cube is by far the most recognized habit followed by the octahedron. Fluorite also has perfect octahedral cleavage. This means that it has four identical directions of cleavage and can produce a perfect octahedral or diamond shape. These cleaved octahedrons are very popular in rock and mineral shops.
Many fluorite specimens exhibit fluorescence under ultraviolet light. In fact the very term ‘fluorescence’ comes from the name ‘fluorite,’ not the other way round, since fluorite was one of the first fluorescent minerals studied. The visible light emitted by fluorite is usually blue, but purple, red, yellow, white and green also occur.
The name fluorite comes originally from the use of fluorite as a flux to lower the melting point in steel and aluminum processing. It was originally referred to as fluorospar by miners. Fluorite has other important industrial uses, such as a source of fluorine for hydrofluoric acid and fluorinated water.
Fluorite has been used instead of glass in some high performance telescopes and camera lenses. Because fluorite has a very low dispersion, light diffraction is less than ordinary glass, and in telescopes it allows sharp imaging of astronomical objects even at high power.
Fluorite is of interest as a gemstone because of its remarkable range of colors and its attractive vitreous luster. Most specimens of fluorite have a single color, but many fluorites have multiple colors and the colors are arranged in bands or zones. But fluorite is quite a soft stone, rating only 4 on the Mohs scal. So it is not very practical for some types of jewelry such as rings, though it serves very well for pendants, earrings and brooches.
Purple or violet is the classic fluorite color, often rivaling amethyst for richness. Blue fluorite is fairly rare, and much sought after by collectors. The brilliant yellow is also quite rare. But the rarest fluorite colors are pink, black and colorless. Black fluorite is formed from exposure to radiation during the growth of the crystals. Colorless fluorite, though not especially attractive, is prized by collectors simply for its rarity.
Jimmy is the owner of http://www.fluoritecrystals.com and several other rock and mineral related websites. He has been a rock and gem dealer and for many years