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www.mineralgallery.co.za Minerals F-J |
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Fluorite |
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Name
Fluorite
Chemistry
CaF2, Calcium Fluoride
Uses
Fluorite is also used as a source of fluorine for hydrofluoric acid and fluorinated water. Other uses of fluorite include an uncommon use as a gemstone (low hardness and good cleavage reduce its desirability as a gemstone), ornamental carvings (sometimes misleadingly called Green Quartz) and special optical uses.
Color
A whole bouquet of colors. The range of common colors for fluorite starting from the hallmark color purple, then blue, green, yellow, colorless, brown, pink, black and reddish orange
Hardness
4
Specific gravity
3.0-3.3
Fluorite, calcium fluoride is a major industrial mineral used as a flux in steel making as well as in the preparation of hydrofluoric acid and in the ceramics industry. Mainly used for glasses and enamels.
Fluorite's vitreous, cubic crystals (isometric system) and cleavable, granular masses have a wide color range (often green, blue, or purple) and may fluoresce under ultraviolet light. Hardness is 4, specific gravity 3.0-3.3. Fluorite deposits form under a wide variety of conditions: as veins produced by hydrothermal alteration, as beds and cavities in sedimentary rocks, in hot spring deposits, and in pegmatites.
It forms the typical cube and to a lesser extent, the octahedron as well as combinations of these two and other rarer isometric habits. Always with equate crystals; less common are crusts and botryoidal forms. Twinning also produces penetration twins that look like two cubes grown together.
Cleavage is perfect in 4 directions forming octahedrons.
Sometimes the less common habits such as a colored octahedron are seen inside of a colorless cube. One crystal of Fluorite could potentially have four or five different color zones or bands.
Fluorite is frequently fluorescent and, like its normal light colors, its fluorescent colors are extremely variable. Typically it fluoresces blue but other fluorescent colors include yellow, green, red, white and purple. The word fluorescent was derived from fluorite since specimens of Fluorite were some of the first fluorescent specimens ever studied.
The naming followed the naming precedence set by opalescence from opal; ergo fluorescence from Fluorite.
Another unique luminescent property of fluorite is its thermoluminescence. Thermoluminescence is the ability to glow when heated. Not all fluorites do this, in fact it is quite a rare phenomenon. A variety of fluorite known as "chlorophane" can demonstrate this property very well and will even thermoluminesce while the specimen is held in a person's hand activated by the person's own body heat (of course in a dark room, as it is not bright enough to be seen in daylight). The thermoluminescence is green to blue-green and can be produced on the coils of a heater or electric stove top. Once seen, the glow will fade away and can no longer by seen in the same specimen again. It is a one shot deal.
Fluorite has other qualities besides its great color assortments that make it a popular mineral. It has several different crystal habits that always produce well formed, good, clean crystals. The cube is by far the most recognized habit of fluorite followed by the octahedron which is believed to form at higher temperatures than the cube. Although the cleavage of fluorite can produce an octahedral shape and these cleaved octahedrons are popular in rock shops the world over, the natural (e.g. uncleaved) octahedrons are harder to find.
Fluorite, as mention above, has octahedral cleavage. This means that it has four identical directions of cleavage and when cleaved in the right ways can produce a perfect octahedral shape. Many thousands of octahedrons are produced from massive or large undesirable crystals of fluorite (hopefully!) and are sold in rock shops and museum gift shops at a small cost. Fluorite mine workers are reported to sit down at lunch breaks and cleave the octahedrons for the extra cash. The octahedrons are very popular due to their attractive colors, clarity, "diamond-shaped" and low costs, but to a serious collector they are nothing more than "cleavage fragments".
Fluorite not only is attractive in its own right but is often associated with other attractive minerals. Fluorite crystals will frequently accompany specimens of silver gray galena, brassy yellow pyrite, chalcopyrite or marcasite, golden barite, black sparkling sphalerite, intricately crystallized calcite and crystal clear quartz, even amethyst.
The origin of the word fluorite comes from the use of fluorite as a flux in steel and aluminum processing. It was originally referred to as fluorospar by miners and is still called that today.Fluorite is the most popular mineral for mineral collectors in the world, second only to quartz. Every mineral collection owned by even the newest and youngest of mineral collectors must have a specimen of fluorite. Fluorite is by far one of the most beautiful and interesting minerals available on the mineral markets
