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Gemstones 250x250

The Mineral fluorite

Green Fluorite Octahedrons

Fluorite is a very popular mineral, and it naturally occurs in all colors of the spectrum. It is one of the most varied colored minerals in the mineral kingdom, and the colors may be very intense and almost electric. Pure Fluorite is colorless; the color variations are caused by various impurities. Some colors are deeply colored, and are especially pretty in large well-formed crystals, which Fluorite often forms. Sometimes coloring is caused by hydrocarbons, which can be removed from a specimen by heating. Some dealers may apply oil treatment upon amateur Fluorite specimens to enhance luster.

Fluorite has interesting cleavage habits. The perfect cleavage parallel to the octahedral faces can sometimes be peeled off to smooth out a crystal into a perfect octahedron. Many crystals, especially larger ones, have their edges or sections chipped off because of the cleavage.

Fluorite is one of the more famous fluorescent minerals. Many specimens strongly fluoresce, in a great variation of color. In fact, the word "fluorescent" is derived from the mineral Fluorite. The name of the element fluorine is also derived from Fluorite, as Fluorite is by far the most common and well-known fluorine mineral.

For additional information, see the gemstones section on Fluorite.

Chemical Formula

CaF2

Color

Fluorite occurs in all colors, including colorless, white, purple, blue, red, pink, orange, yellow, brown, green, gray, and black. May also be multicolored and banded.

Crystal System

Isometric

Properties

Streak
White
Hardness
4
Transparency
Transparent to translucent
Specific Gravity
3.0 - 3.3
Luster
Vitreous
Cleavage
1, all sides
Fracture
Conchoidal
Tenacity
Brittle
Other ID Marks
Commonly fluorescent in a variety of colors.

Crystal Habits

Most commonly octahedrals and cubic; seldom in dodecahedral crystals. Crystals may also be a combination of octahedra and cubes, and dodecahedral growths may also be present, forming complex and interesting crystals. Cleavage marks are present on most crystals. Cleavage fragments from large crystals are also prevalent; in octahedra, the cleavage fragments are flat, triangular shaped pieces, and cubic cleavage fragments are flat, three dimensional rectangles. Crystals frequently form penetration twins, where one cube is intergrown in another ("fluorite twins"). Also occurs as clusters of intergrown cubes, grainy, botryoidal, as spherical balls, and massive.

3D Crystal Atlas

Additional Information

Composition
Calcium fluoride
In Group
Halides
Striking Features
Perfect cleavage, low hardness, and crystal habits
Environment
Hydrothermal ore veins, sedimentary deposits, metamorphic environments, and pegmatite dikes.
Rock Type
Igneous, Sedimentary, Metamorphic

Varieties

 -   Variety of Fluorite containing uncombined fluorine ions. When fractured or cleaved, this variety gives off a peculiar odor.
 -   Banded purple and white (or purple and yellow) variety of Fluorite.
 -   Variety of Fluorite that is thermoluminescent, emitting bright green light when heated.
 -   Variety of Fluorite in which the elements cerium and yttrium partially replace the calcium in the chemical structure. Its chemical formula is (Ca,Ce,Y)F2.
 -   Variety of Fluorite in which the element yttrium partially replaces the calcium in its chemical structure. Its chemical formula is (Ca,Y)F2.

Uses

Fluorite is the only mineral for which significant quantities of the important element fluorine can be obtained. Fluorite is also used as a flux in the manufacture of steel and other metals to eliminate impurities. There is a great demand for Fluorite in the optics field, and to meet it synthetic crystals are grown to produce special lenses. It is used in the production of certain glass and enamel.

Ornamental objects have been found carved from Fluorite. It is soft and creates beautiful ornaments if a large enough chunk is found. Fluorite very often occurs in unflawed crystals in beautiful colors, but its softness prevents it from being a gemstone and it is only faceted for collectors. Fluorite is a very popular mineral among collectors, especially those of classic occurrences which can command exorbitant prices.

Noteworthy Localities

Fluorite occurs throughout the world, and is a very common mineral. Only classic and exceptional localities will be listed here. England has produced some of the finest specimens, especially in Weadale, North Pennines, Co. Durham. Green cubic crystals have come from the famous Rogerly Mine in Weardale, and these uniquely exhibit daylight fluorescence, changing to a saturated blue color in sunlight. Other English occurrences in the North Pennines region are Nenthead (Alston Moor District); the Hilton Mine, Scordale; and East Allendale (Allenheads Mine and St. Peters Mine).

Bright blue Fluorite crystals are known from several areas in France. Three particular important localities are Le Burg (Le Burc) and Mont-Roc, both in Tarn, and Le Beix, in Puy-de-Dome. Pink octahedrons, highly valued by collectors, were found in the Alps near the Argentiere Glacier, Mont Blanc, Chamonix, France; and at Göscheneralp, Uri, Switzerland. Fine crystals are also found in Spain in Caravia, Asturias, especially in the Berbes, La Collada, and Villabona areas. In Germany, fine Fluorite has come from the Erzgebirge in Saxony at Frohnau and the Freiberg District.

Excellent Fluorite specimens are well known from Dal'negorsk, Primorskiy Kray, Russia, and these are very highly regarded by collectors. China has become an excellent producer of Fluorite, with notable occurrences at the Yaogangxian mine, Hunan Province; Shangrao (De'An), Jiangxi Province; the Huanggang Mine, Inner Mongolia; and the Shangbao Mine, Hunan Province. Rounded botryoidal balls, a rare form for Fluorite, comes from Mahodari, Nasik District, Maharashtra, India.

In South Africa, excellent deep-green Fluorites were recently discovered in Riemvasmaak, Northern Cape Province. This occurrence has become one of the most popular Fluorite localities in recent times. The Erongo Mountains of Namibia have produced a highly desirable and unique habit of green Fluorite in cuboctahedral form with an "alien eye" appearance.

In South America, excellent Peruvian localities include the Pasto Bueno District, Pallasca Province, Ancash; and the Huanzala Mine, Huallanca District, Huanuco. Mexico has some fine notable Fluorite locations, specifically Naica, Chihuahua; Melchor Muzquiz, Coahuila; and Mapimi and Navidad, Durango. Canada has produced some some fine crystals, in the Rock Candy Mine, Grand Forks, British Columbia.

The U.S. also contains numerous fine Fluorite occurrences. Hardin Co., Illinois, has produced more collectible specimens than anywhere in the U.S., and the locations of Rosiclare, Cave In Rock, and the Harris Creek District (Denton and Annabel Lee Mines) are very famous. Other excellent Fluorite deposits are Marion, Crittenden Co., Kentucky; Clay Center, Ottawa Co., Ohio; the Elmwood Mine, Carthage, Smith Co., Tennessee; Grant Co., New Mexico; and Walworth, Wayne Co., New York. Excellent green octahedrons are found in Westmoreland, New Hampshire. Another very important occurrence is the Blanchard Mine, Bingham, Socorro Co., New Mexico.

Common Mineral Associations

Calcite, Quartz, Barite, Galena, Pyrite, Chalcopyrite

Distingushing Similar Minerals

Calcite - Slightly softer (3), different crystal forms.
Quartz - Much harder (7), no cleavage.
Apatite - Harder (5), different crystal form.
Halite - Softer (2 - 2½), has a salty taste.


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