Updates? Our editors will review what you’ve submitted and determine whether to revise the article. CaF2 (Fluorite) has an arrangement where the fluorides are 4 coordinate and the Calcium is eight coordinate. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. Corrections? The Structure of Fluorite - Calcium difluoride, CaF2. Some fluoride anions may be replaced b… Let us know if you have suggestions to improve this article (requires login). Premium Membership is now 50% off! Fluorite has four perfect cleavage planes that help produce octahedral fragments. Black Friday Sale! Many compounds, notably the common mineral fluorite (CaF 2), adopt this structure. Iron, sodium, and barium are also common impurities. If the cations have CN=4 and the anions have CN=8 this is described as an antifluorite structure, examples include Li 2 O and Na 2 O. For detailed physical properties, see halide mineral (table). Element substitution for the calcium cation often includes certain rare earth elements(REE), such as yttrium and cerium. Magnesium compounds such as Mg 2 X, where X can be one of the elements Si, Ge, Sn, or Pb, are said to have an antifluorite structure because the locations of the anions and cations are reversed relative to fluorite (an anti-structure ); the anions occupy the FCC regular sites whereas the cations occupy the … The structural motif adopted by fluorite is so common that the motif is called the fluorite structure. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Fluorite is used as a flux in the manufacture of open-hearth steel, of aluminum fluoride, of artificial cryolite, and of aluminum. This article was most recently revised and updated by, https://www.britannica.com/science/fluorite, University of Wisconsin-Extension - Fluorite, The Mineral and Gemstone Kingdom - Fluorite, Amethyst Galleries' Mineral Gallery - Fluorite. It is used in opalescent glass, in iron and steel enamelware, in the production of hydrofluoric acid, in the refining of lead and antimony, and in the manufacture of high-octane fuels (as a catalyst). Omissions? China and Mexico are the world’s major producers of flourite; the mineral is also widespread in Russia, Brazil, and Spain. Fluorite, also called fluorspar, common halide mineral, calcium fluoride (CaF2), which is the principal fluorine mineral. Generally, if the radius ratio r-/r+ exceeds ~1.37 then a rutile rather than fluorite structure is favoured. Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... …have the same structure as fluorite (CaF, …almost the only source was fluorspar (CaF, …was derived from the mineral fluorspar, which exhibits a violet, short-duration luminescence on irradiation by ultraviolet light.…. 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. Crystal twinning is common and adds complexity to the observed crystal habits. 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. Because of its low index of refraction and low dispersion, clear colourless fluorite of optical quality is used for apochromatic lenses. At one time blue john, a variety from Derbyshire, England, was widely used in ornamental vases and other objects. It is usually quite pure, but as much as 20 percent yttrium or cerium may replace calcium. Fluorite crystallizes in a cubic motif.

6 By 9 Subwoofers, Plastic Surgery Nurse Practitioner Salary, Who Invented Money, Black Girl Silhouette Art, Gujarati Sambharo Recipe, Tuna Mayo Sandwich,