apatite

noun1

1. •
   A calcium fluoride phosphate of variable composition, sometimes used in the manufacture of fertilizer, as a gemstone, and (in powdered form) as a pigment, and also produced biologically in bones and teeth.

   • We had prepared, by precipitation methods, finely divided crystalline apatites that were similar in crystal size and x-ray diffraction profile to bone apatite. — 1967