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A member of the phosphate group of minerals, the world's major source of phosphorus, found as variously coloured, glassy crystals, masses, or nodules. Much of it has a chemical composition approximating Ca(PO)(F,Cl,OH). If not for its softness, apatite would be a popular gemstone; some of the material found is clear, but it is fragile and difficult to cut and polish.
This entry comes from Encyclopædia Britannica Concise. For the full entry on apatite, visit Britannica.com.