Home Minerals Halide Fluorite

Fluorite

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Fluorite is a halide mineral with chemical formula is calcium fluoride (CaF2). Also called fluorspar. It is usually quite pure, but as much as 20 percent yttrium or cerium may replace calcium. Fluorite occurs most commonly as a glassy, many-hued vein mineral and is often associated with lead and silver ores; it also occurs in cavities, in sedimentary rocks, in pegmatites, and in hot-spring areas

An important industrial mineral. Fluorite commonly occurs as vibrant, well-formed crystals. A single crystal may have zones of different colors that follow the contour of the crystal faces. Fluorite crystals are widely found in cubes, while fluorite octahedra which are often twinned are much less common. The mineral can also be massive, granular, or compact. Fluorite occurs in hydrothermal deposits and as an accessory mineral in intermediate intrusive and silica-rich rocks. It is used in the manufacture of high-octane fuels and steel and in the production of hydrofluoric acid. (Bonewitz, 2012)

Name: From the Latin to flow, in allusion to its low melting point.

Cell Data: Space Group: Fm3m. a = 5.4626 Z = 4

Association: Quartz, dolomite, calcite, barite, celestine, sulfides, cassiterite, topaz, wolframite, scheelite, apatite.

Crystallography: Isometric; hexoctahedral. Habit cubic, often in twinned cubes. Other forms are rare, but examples of all the forms of the hexoctahedral class have been observed; the tetrahexahedron and hexoctahedron are characteristic. Usually in crystals or in cleavable masses. Also massive; coarse or fine granular; columnar.

Fluorite Composition: Calcium fluoride, CaF2. Ca = 51.1 percent, F = 48.9 percent.

Diagnostic Features. Determined usually by its cubic crystals and octahedral cleavage; also vitreous luster and usually fine coloring, and by the fact that it can be scratched with a knife.

Chemical Properties

Chemical Classification Halide mineral
Chemical Composition CaF2

Fluorite Physical Properties

Color Colorless, although samples are often deeply colored owing to impurities.
Streak White
Luster Vitreous
Diaphaneity Transparent to translucent       
Mohs Hardness 4 (defining mineral)
Specific Gravity 3.175–3.184
Diagnostic Properties May be fluorescent, phosphorescent, thermoluminescencent, and/or triboluminescent
Crystal System Isometric

Fluorite Optical Properties

Optical Properties of Fluorite : under PPL
Type Isotropic
RI values n = 1.433 – 1.448
Twinning Common
Dispersion None
Birefringence Isotropic minerals have no birefringence
Relief Moderate

Occurrence

Most fluorite occurs as vein fillings in rocks that have been subjected to hydrothermal activity. These veins often contain metallic ores which can include sulfides of tin, silver, lead, zinc, copper, and other metals. It is also found in the fractures and vugs of some limestones and dolomites. It can be massive, granular, or euhedral as octahedral or cubic crystals. It is a common mineral in hydrothermal and carbonate rocks worldwide.

Fluorite Uses

  • Numerous uses in the metallurgical,
  • ceramics, and chemical industries.
  • A source of fluorine, hydrofluoric acid, metallurgical flux.
  • igh-clarity pieces are used to make lenses for microscopes, telescopes, and cameras.

Distribution

Notable occurrences include: in England, from many localities

  • in Cornwall; in Durham, as at Weardale; from Castleton, Derbyshire. In France, at Bex, Var; Le Beix, Puy de Dome; and on Mont Blanc, near Chamonix, Haute-Savoie.
  • On the Goscheneralp, Uri, Switzerland.
  • From Wolsendorf, Bavaria, and in the Clara Mine, near Oberwolfach, Black Forest, Germany.
  • Around Berbes, Asturias Province, Spain.
  • At the Nikolaev mine, Dalnegorsk, Russia.
  • From Kara Oba, Kazakhstan.
  • At Xianghuapu, Hunan Province, China.
  • In Mexico, from Naica, Chihuahua; Musquiz, Coahuila; and the Ojuela mine, Mapimı, Durango.
  • In the USA, from Macomb, St. Lawrence Co., and Penfield, Monroe Co., New York; at Clay Center, Ottawa Co., Ohio; from Rosiclare and Cave-in-Rock, Hardin Co., Illinois; at the Elmwood mine, Smith Co., Tennessee; in the Sunnyside mine, San Juan Co., Colorado; from the Pine Canyon deposit, Burro Mountains, Grant Co., New Mexico.
  • In Canada, from Madoc, Ontario, and in the Rock Candy mine, near Grand Forks, British Columbia.
  • From Huanzala, Huanuco, Peru.
  • At Okorusu, Namibia. In Pakistan, at Nagar, near Karimabad, Gilgit district.

References

  • Bonewitz, R. (2012). Rocks and minerals. 2nd ed. London: DK Publishing.
  • Dana, J. D. (1864). Manual of Mineralogy… Wiley.
  • Handbook of Mineralogy. [online] Available at: http://www.handbookofmineralogy.org [Accessed 4 Mar. 2019].
  • Mineral information, data and localities.. [online] Available at: https://www.mindat.org/ [Accessed. 2019].
Cite this article as: Geology Science. (2019). Fluorite. [online] Available at: http://geologyscience.com/minerals/fluorite/ [9th December 2019 ]
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