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The chemical formula of Fluorite is indicated by the formula CaF2 or Calcium Fluoride. Fluorite is a Halide mineral. It commonly exhibits a moderately high negative relief when viewed closely under petrographic polarizing microscopes. Mineral Fluorite has a face-centered cubic structure. Fluorite is usually used as a flux in iron smelting. Fluorite is also a source of fluorine. This mineral is usually found with a veritable bouquet of brilliant colors that are usually beautifully displayed under petrographic polarizing light microscopes. Fluorite is commonly prized and popular due to its rich variety of colors and also for its glassy luster in reflected light of polarizing light microscopes for geologists. Fluorite mineral species was first discovered in Bohemia, Czech Republic in the year 1529. The name Fluorite is derived from the use of fluorite as flux in steel and aluminum processing and also from the Latin word fluere, which means to flow. Originally, the name referred to as fluorospar by many mineral miners and it is still referred that way at present. Fluorite is also uncommonly used for gemstone purposes because of its low hardness and good cleavage. It is also rarely used for ornamental carvings but may sometimes misleadingly call as Green Quartz. Fluorite has also special optical uses.

 

Fluorite is commonly colorless, blue, green, or purple. But then any color is possible for Fluorite usually ranging from the hallmark color purple, then blue, green, yellow, brown, colorless, reddish orange, black and pink. These colors are usually amazingly displayed under polarizing light microscopes and this color range is only rivaled by quartz. The intermediate pastel colors between the previously mentioned colors can be also possibly found. And because of this variety of wonderful colors displayed by the mineral, it has earned the reputation of being The Most Colorful Mineral in the World. But then Fluorite is usually found colorless in thin section or grain mount. The pale colors correspond most commonly to hand sample colors that may be visible in some cases. Colored samples may appear blotchy or zoned parallel to the crystal faces. There is no pleochroism displayed because Fluorite is an isotropic mineral. Fluorite commonly vitreous luster is reflected light of petrographic polarizing microscope. Flourite usually exhibits an irregular and brittle fracture. Its hardness measure when it is evaluated using the Mohs scale method is usually found 4. When it is rubbed on a white porcelain steak plate, it commonly leaves a white streak. The specific gravity measure of the mineral is commonly found 3.18 grams per cubic centimeters, which is considered average. Fluorite usually fluoresces in both short wave and long wave ultraviolet light. Some samples of Calcite may show phosphorescent.

 

Fluorite is most commonly found having perfect octahedral cleavage at {111} found in four directions and usually found clearly visible when viewed closely with the aid of polarizing microscopes for mineralogist. This octahedral cleavage of Fluorite is found forming four identical directions of cleavage planes that when cleaved in the right ways will certainly produced a perfect octahedron. There are also some penetration twins found by rotation on {111}. These twins are common but they will not be found visible in thin section or fragments unless belied by crystal shape or color zoning.

 

            Most Fluorite mineral specimens are found having one single color but some other Fluorite minerals are found with multiple colors that are arranged in zones or bands that also correspond to the shape of the Fluorite mineral crystal. This simply means that when a Fluorite mineral is found with its typical cube crystal habit, its color zones are also arranged in cubic arrangements. The result will then be similar to that of the phantomed crystals that appear to be having crystals within crystals and they are often found having different colors most especially when they are viewed under geological polarizing light microscopes. There is also a Fluorite crystal that could have a clear outer zone almost allowing the purple cube crystal of Fluorite to be seen clearly inside most especially when viewed under polarized light microscopes. There can be also some time when the less common crystal habit of Fluorite, which is octahedron, can be also seen clearly inside the colorless cube crystal. One Fluorite crystal is already a potential bearer of five or more different color zones or bands that are commonly splendidly exhibited under a polarizing microscope for geologists.

 

Mineral Fluorite is known to crystallize in the isometric system. This crystal system comprises crystals having three axes, all of which are perpendicular to one another and all are found equal in lengths. Most Fluorite mineral crystals are found transparent to translucent in appearance. The crystal habit of the mineral usually include typical cube, also octahedron as well as combinations of this two and several other isometric habits. Cube or cubes modified by octahedral or dodecahedral faces are common. Fluorite also forms anhedral grains or granular masses, or occasionally columnar or fibrous aggregates. Fluorite mineral crystals are always found with equant crystals that can be found clearly visible when viewed with the aid of polarized light microscopes. Fluorite is less commonly found in crust form or botryoidal form. The twinned crystals of mineral Fluorite commonly produces penetration twins which appear like two cubes that were grown together. This habit of Fluorite mineral is commonly clearly visible when the specimen is evaluated with the aid of petrographic polarizing microscopes.

 

            Mineral Fluorite is also commonly found fluorescent in ultra violet light. Some other Fluorite varieties can actually demonstrate phosphorescence in a third color. This simply indicates almost four possible color luminescence in just one specimen. The blue fluorescence of the mineral Fluorite has been attributed to the traces of europium that is found in its chemical composition. The yellow fluorescence on the other hand is activated by the element Yttrium. While the red and green fluorescence is not yet identified exactly if of what activation. Some mineralogists suggest that it could be the effect of the unbonded fluorine that is trapped in the chemical structure of the mineral. The term fluorescent was actually derived from fluorite because this was the very first fluorescent mineral specimen that has been found and studied. It also followed the naming precedence set by opalescence from opal, hence fluorescence from fluorite. Thermoluminescence is another unique property possessed by mineral Fluorite. This property is the ability of the mineral crystals to glow when subject to heat. But then not all Fluorite specimens exhibit this property. But then this thermoluminescence is only clearly exhibited in a dark location and it could not glow brightly in daylight.

 

            Fluorite is an isotropic mineral. This means that it remain dark when viewed in any angle between crossed nicols of petrographic polarizing microscopes. The refractive index of Fluorite commonly ranges from 1.433 to 1.448. Most Fluorite actually have index 1.434 But when calcium is substituted by yttrium, the index of refraction of Fluorite will increase up to 1.457. This mineral has no dispersion displayed. Most frequently, Fluorite is found exhibiting a weak anomalous birefringence especially in cleaved, cut or pressed crystals. Mineral Fluorite is commonly found associated with other interesting minerals including pyrite, calcite, galena, quartz, sphalerite, willemite, apatite, barite, chalcopyrite, witherite and other sulfide minerals. There is no specific data found on the toxicity and health dangers for mineral Fluorite. However, the specimens of this mineral should be treated with great care and use of sensible precaution is advised upon handling them. Fluorite is a non-radioactive mineral.

 

Fluorite is commonly found in hydrothermal veins as well as in cavities in sedimentary rocks and also in hot spring deposits. They are relatively common in some hydrothermal mineral deposits associated with sulfide minerals. Sometimes Fluorite can be found as an accessory mineral to related igneous rocks as well as granite, syenite, and granite pegmatite. The best field indicators of mineral Fluorite usually include color zoning, hardness, crystal habit, fluorescence and its octahedral cleavage. Chlorophane Fluorite mineral specimens can be only found in limited quantities at some mineral localities including Mont Saint-Hilaire in Quebec, Canada as well as Gilgit in Pakistan, Nerchinsk in the Ural Mountains in Russia, at Amelia Court House in Virginia, Franklin in New Jersey and the Bluebird Mine in Arizona, USA. Fluorite minerals also notably occur at several other localities like Spain, China, Cumberland in England, Brazil, Canada, Mexico and many localities in the United States including Colorado, Ohio, Indian, Illinois, Tennessee, and many more.



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Monday, March 24th, 2008 at 4:25 am
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The Halides Mineral Class
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