Euhedral to subhedral crystals of blue apatite from 1 to 7 cm long occur in a partly serpentinized marble from a quarry near Matale, north-ccntral Ceylon.

The chemical composition of the apatite is as follows: CaO 55.24, MnO 0.02, P2O5 40.91, F 1.05, Cl 2.31, H2O 0.68, CO2 1.18, Fe2O3 0.03, 0 ≡ F, Cl 1.17, total 100.25 percent. The calculated cell contents on the basis of 26(O, OH, F, Cl) are
Ca9.93(PO4)5.81(CO3)0.27(OH0.76,Cl0.66,F0.56)

which corresponds to the theoretical formula Ca5(PO4)3(OH, F, Cl); the ratio F:Cl:OH is 1.0.1.17.1.36. The composition, as determined, is unusual, and warrants the name carbonate-bearing fluor-chlor-hydroxyapatite. The other properties are ϵ 1.646, ω 1.651, density (at 25°C) 3.18.

The apatite crystals are thought to have been formed during regional metamorphism, under granulite facies conditions, of a phosphatic sedimentary limestone.

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