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.
which corresponds to the theoretical formula Ca5(PO4)3(OH, F, Cl); the ratio F:Cl:OH is 220.127.116.11.1.36. 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.