"Apatite is an accumulation of phosphate minerals, usually referring to hydroxyapatite, fluorapatite, and chlorapatite, with extraordinary concentrations of OH−, F−, and Cl− ions, individually, in the crystal. The formula of the admixture of the three most prevalent endmembers is formulated as Ca10(PO4)6(OH, F, Cl)2, and the crystal assembly cell formulae of the unique minerals are written as Ca10(PO4)6(OH)2, Ca10(PO4)6F2 and Ca10(PO4)6Cl2. The mineral was named apatite by the German geologist Abraham Gottlob Werner in 1786, although the special mineral he had expressed was reclassified as fluorapatite in 1860 by A great German mineralogist Karl Friedrich August Rammelsberg. Apatite is often misunderstood for other minerals. This current is reflected in the mineral's name, which is derived from the Greek word απατείν (apatein), which means to deceive or to be misleading."