Fluorapatite

Fluorapatite is a calcium phosphate mineral in the apatite group, with fluoride ions occupying channels in its crystal structure. Its ideal formula is Ca₅(PO₄)₃F.

Apatite: A group of phosphate minerals with the general formula Ca₅(PO₄)₃(X), where X is commonly fluoride, chloride, or hydroxide. Fluorapatite is the fluoride-rich member of this mineral group.
Isomorphous substitution: Replacement of one ion by another in a mineral crystal without substantially changing its structure. Fluoride can occupy apatite's anion sites in place of hydroxide or chloride.
Phosphate rock: A sedimentary rock rich in phosphate minerals, mined chiefly to produce fertilizer. Fluorapatite is a common phosphate-bearing mineral in many phosphate deposits.
Pegmatite: An exceptionally coarse-grained igneous rock, commonly associated with the late stages of magma crystallization. Large fluorapatite crystals can grow in pegmatites.
Apatite crystal structure: A hexagonal arrangement of calcium and phosphate groups with channels that host anions. The channels provide the sites occupied by fluoride in fluorapatite.
Mineral precipitation: Formation of a solid mineral from ions dissolved in a fluid when conditions favor crystal growth. Fluorapatite can crystallize from fluoride- and phosphate-bearing fluids.
Phosphorite: A sedimentary rock composed largely of phosphate minerals, often formed in marine environments. Fluorapatite occurs as a major mineral component in many phosphorites.
Carbonatite: An igneous rock composed of more than half carbonate minerals by volume. Some carbonatites contain fluorapatite as a major phosphate mineral.
Hydroxylapatite: A calcium phosphate mineral in which hydroxide occupies the anion sites characteristic of apatite. Replacing fluorine with hydroxide distinguishes this closely related apatite mineral.
Solubility product: An equilibrium constant describing the ion concentrations at which a sparingly soluble solid dissolves or precipitates. It helps describe conditions under which fluorapatite forms or dissolves.

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