Calcium Hydroxyapatite; Ca10(PO4)6(OH)2Structure consists of calcium surrounded by phosphate and hydroxy groups…A complete unit cell is not shown here, instead you can see distinguishing features such as: PO4 tetrahedra, O-H groups, calciumThe unit cell consists of two triangular prismatic subcells forming a rhombic prism with vertical sides. There are two horizontal mirror planes, one 1/4 of the way down and one 3/4 of the way down from the top. In addition, there is a center of inversion exactly in thecenter of each vertical face of each subcell.we see a CaO9 substructure centered on Ca1. The three O1 atoms are above the Ca atom; the three O2 atoms, slightly twisted, are below. The three O3 atoms are slightly below the Ca1 atom in this view.The six PO4 units of the unit cell (three in each of the two triangular subcells) are organized in sets of three in a "pinwheel" fashion around Ca1. They are attached via O2 and O3 in each case. In this depiction there are two O3 atoms aligned vertically. One is part of the enantiomeric CaO9 unit just above this oneAlong each of the three vertical faces of each triangular subcell there are two calcium atoms of another sort (Ca2), each with seven O atoms nearby, making a