Philipsburgite from the Yamato mine, Yamaguchi Prefecture, Japan

Abstract

Philipsburgite, (Cu,Zn)5Zn(AsO4,PO4)2(OH)6·H2O, an As analogue of kipushite, was discovered in the Yamato mine, Yamaguchi Prefecture, Japan. Philipsburgite occurs in the form of spherical aggregates, 0.5 mm in diameter, with bright green in color. It is associated with malachite and cornwallite in cavities of the oxidized rocks, which consist of quartz and goethite. Spherical philipsburgite consists of platy crystals, 100 μm in length and 1 μm in thickness, with sharp termination. The empirical formula is (Cu4.91,Zn0.09)Σ5.00Zn1.00[(AsO4)1.63(PO4)0.37]Σ2.00(OH)6·1.60H2O on the basis of O = 11 in the anhydrous part per formula unit and the water content was measured by thermogravimetric analysis. The composition is closest to the As end member thus far reported. The unit cell parameters from the X-ray diffraction data are a = 12.359(8), b = 9.247(7), c = 10.734(5) Å, β = 97.22(5)° and V = 1216.9(9) Å3.