Hydroxylellestadite, A New Apatite from Chichibu Mine, Saitama Prefecture, Japan Available to Purchase

Chemical analysis by K.N. and K.N. gave CaO 54.51, MgO, trace, MnO 0.04, SrO 0.28, Na₂O, 0.34, K₂O 0.07, CO₂1.65, P₂O₆ 0.66, SiO₂17.30, SO₃ 21.56, Al₂O₃ trace, Fe₂O₃ 0.21, F 0.28, Cl 0.91, H₂O⁺ 2.04, H₂O⁻ 0.72, −0 = F₂, Cl₂0.32, total 100.25, corresponding to

or ideally Ca₁₀((SiO₄)₃(SO₄)₃)(OH, Cl, F)₂ with OH>Cl, F. This is the OH analogue of ellestadite, which has Cl>OH, F. X-ray powder data as well as precession photographs showed it to be hexagonal, with space group $C6h2−P63/m$⁠, with a 9.491 Å, c 6.921 Å (both ± 0.001 Å), and Z = 1. Synthetic Ca₁₀((SiO₄)₃(SO₄)₃)(OH)₂ has a 9.484, c 6.927 (Takemoto and Kato, 1968). The strongest lines are 3.462(40)(0002), 2.839(100)(21.1), 2.801(44)(11.2), 2.739(60)(30.1), 2.655(45)(20.2), 1.853(43)(21.3), 1.484(20)(50.2). Optically hydroxylellestadite is uniaxially negative, with ϵ 1.650 and ω 1.654 (both α0.001). DTA, TGA, and IR data are given.

Mineral data and modes of occurrences of pale rose-pink wilkeite from Takiue as well as of yellowish green OH-Cl-F-apatite from Uzunosawa, both in the Chichibu Mining Area, are also described.