The Apatite Group of Minerals




The Apatite Group minerals are a group of phosphates, arsenates and vanadates that have very similar hexagonal or pseudohexagonal monoclinic structures. This group includes several important and colorful minerals such as apatite (from where this group gets its name), mimetite, pyromorphite and vanadinite; all pictured above. Apatite is a general name for three official minerals named chlorapatite, fluorapatite and hydroxylapatite.

The general formula for the group is A5(BO4)3 (OH, F, Cl). The A cations can be any of several metal ions such as calcium, barium, sodium, lead, strontium, lanthanum and/or cerium. The B cations can be either phosphorous, vanadium or arsenic. Carbonate anion groups, CO3, and silicate anion groups, SiO4, can substitute to a limited extent for the BO4 groups.


The silicate minerals britholite-(Ce), britholite-(Y), chlorellestadite, fluorellestadite, hydroxylellestadite and mattheddleite and the sulfate mineral cesanite are isostructural with this group, but are generally not considered apart of the Apatite Group.
 


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