1Tectonics, Resources and Exploration (TRaX), School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia2South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia
(PO4)3(OH)3, has been solved and refined from single-crystal X-ray data collected on a Sr-bearing sample from the Spring Creek copper mine, near Wilmington, South Australia. A fragment of the crystal used for the collection of the X-ray intensity data was analysed by electron microprobe. The resulting unit formula is (Ba1.00,Sr0.03)Σ1.03(
,Al0.06)Σ2.00(PO4)2.99(OH)3.04. The structure is monoclinic, space group P21/m, a = 9.2425(18), b = 12.470(3), c = 5.002(1) Å, β = 100.19(3)°, V = 567.41(19) Å3, Z = 2, and was refined to R1 = 4.71% for 1568 unique observed reflections. The X site is -coordinated and is occupied by dominant Ba and minor Sr, with an <X–O> distance of 2.953 Å. The M1 site is octahedrally coordinated and is occupied by Mn2+ and Fe2+ plus minor Ca, Mg and Na with an observed <M1–O> distance of 2.208 Å. The M2 site is also octahedrally coordinated and is occupied by Fe3+ plus minor Al with a <M2–O> distance of 2.018 Å. Perloffite is isostructural with other members of the bjarebyite group. Edge-linked [M22O6(OH)4] dimers link via corners to form chains along . Chains are decorated with PO4 tetrahedra and link in the a direction via [M1O5(OH)] octahedra and (Ba,Sr) atoms to form a complex framework. The H2 atom hydrogen-bonds strongly to the O3 anion, providing additional linkage between chains.
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