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Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF 2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs scale of mineral hardness, based on scratch hardness comparison, defines value 4 as fluorite.
Sylvite, or sylvine, is potassium chloride (KCl) in natural mineral form. It forms crystals in the isometric system very similar to normal rock salt, halite (Na Cl). The two are, in fact, isomorphous. [5] Sylvite is colorless to white with shades of yellow and red due to inclusions. It has a Mohs hardness of 2.5 and a specific gravity of 1.99.
Two commercially important halide minerals are halite and fluorite. The former is a major source of sodium chloride, in parallel with sodium chloride extracted from sea water or brine wells. Fluorite is a major source of hydrogen fluoride, complementing the supply obtained as a byproduct of the production of fertilizer.
Sodium fluoride and sodium chloride adopt the same structure. For compounds containing more than one fluoride per cation, the structures often deviate from those of the chlorides, as illustrated by the main fluoride mineral fluorite (CaF 2) where the Ca 2+ ions are surrounded by eight F − centers.
Halite is a mineral, the natural form of salt, also known as sodium chloride or table salt.
The fluorite structure refers to a common motif for compounds with the formula MX 2. [1][2] The X ions occupy the eight tetrahedral interstitial sites whereas M ions occupy the regular sites of a face-centered cubic (FCC) structure. Many compounds, notably the common mineral fluorite (CaF 2), adopt this structure.
Sodium fluoride is an inorganic ionic compound, dissolving in water to give separated Na + and F − ions. Like sodium chloride, it crystallizes in a cubic motif where both Na + and F − occupy octahedral coordination sites; [32] [33] its lattice spacing, approximately 462 pm, is smaller than that of sodium chloride (564 pm).
Sodium fluoride: yellow is fluorine, purple is sodium. They are isoelectronic, but fluorine is bigger because its nuclear charge is lower. The alkali metals form monofluorides. All are soluble and have the sodium chloride (rock salt) structure, [47] Because the fluoride anion is basic, many alkali metal fluorides form bifluorides with the ...