Mineral Structure Data
The apatite group is composed of minerals of the general formula Ca5(PO4)3(OH,F,Cl).
The crystal structure of apatite.
End-Member Hydroxyapatite Fluorapatite Chlorapatite
Formula Ca5(PO4)3OH Ca5(PO4)3F Ca5(PO4)3Cl
Form.Wt. 502.322 504.313 520.767
Density 3.153 3.201 3.185
Mol Volume 159.334 157.527 163.527
Z 2 2 2
Cryst.Sys. Hexagonal Hexagonal Hexagonal
Cryst.Class 6/m 6/m 6/m
Space Group P63/m P63/m P63/m
Cell Parameters
a 9.424 9.367 9.628
c 6.879 6.884 6.764
Vol. 529.09 523.09 543.01
Ref. Sudarsanan and Sudarsanan Mackie et al.
Young(1969) et al.(1972) (1972)
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End-Member Hydroxyapatite Fluorapatite Chlorapatite Site Ca1 Ca2 Ca1 Ca2 Ca1 Ca2 C.N. 9 8 9 7 9 8 Point Sym. 3 m 3 m 3 m Wyckoff Not. 4f 6h 4f 6h 4f 6h Frac.Coord. x 1/3 .2465 1/3 .2416 1/3 .2596 y 2/3 .9931 2/3 .0071 2/3 .0053 z .0013 1/4 .0012 1/4 .0038 1/4 Distances O1 (3)2.407 (1)2.705 (3)2.397 (1)2.814 (3)2.398 (1)2.973 O2 (3)2.452 (1)2.357 (3)2.453 (1)2.384 (3)2.448 (1)2.295 O3 (3)2.805 (2)2.344 (3)2.801 (2)2.384 (3)2.789 (2)2.534 O3 (2)2.512 (2)2.398 (2)2.336 OH/F/Cl (2)2.383 (1)2.231 (2)2.801 Mean 2.555 2.443 2.550 2.428 2.545 2.577 sigma .189 .127 .190 .180 .184 .255 Poly.Vol. 31.974 26.138 31.750 21.506 31.977 34.126 Site Energy -969. -1009. -984. -996. -984. -976. |
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End-Member Hydroxyapatite Fluorapatite Chlorapatite C.N. 4 4 4 Point Sym. m m m Wyckoff Not. 6h 6h 6h Frac.Coord. x .3983 .3981 .4078 y .3683 .3688 .3754 z 1/4 1/4 1/4 Distances O1 1.537 1.534 1.536 O2 1.545 1.541 1.542 O3(2) 1.529 1.534 1.529 Mean 1.535 1.536 1.534 sigma .008 .003 .006 Poly.Vol. 1.853 1.857 1.849 Q.E. 1.0011 1.0008 1.0017 Ang.Var. 4.3 3.7 7.1 Site Energy -6831. -6835. -6834. |
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