Minyulite (hydrous K-Al fluophosphate) from South Australia

Abstract

In 1908, at the close of the Franco-British Exhibition at Shepherd's Bush, London, a series of rock phosphates from various localities in South Australia was transferred to the Mineral Department of the British Museum as a present from the Government of South Australia. One large block from Wait's quarry at Noarlunga, 20 miles south of Adelaide, showed cavities lined with crusts of minute crystals. These crystals were determined goniometrically and optically in 1908 to be orthorhombic, and qualitative chemical tests showed the presence of Al, Mg, P, F, and H2O (K was missed). This evidently represented a new mineral, and it is only now that the work has been successfully completed by the three junior authors. In the meantime, however, the same mineral was discovered in Western Australia by the late Dr. E. S. Simpson in 1932, and named minyulite, from Minyulo Well. This he determined optically to be orthorhombie, and the formula was given as KAl2(OH,F)(PO4)2.3½H2O or 2K(OH, F).4A1PO4.7H2O. Crystallographic and X-ray data are now given for this species.