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May-June 2011

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Who's Who in Mineral Names: William “Bill” David Birch (b. 1949)

Birchite, Cd2Cu2(PO4)2(SO4)·5H2O, was discovered on oxidized ore from the Block 14 open-cut mine, which had been transported to the Pinnacles mine, 15 kilometers southwest of Broken Hill, New South Wales (Elliott et al. 2008). Birchite formed here through the oxidation of primary lead-zinc sulfide ore. It occurs in small cavities and thin seams in quartz-garnet matrix that contain disseminated corroded masses of galena and fluorapatite. Birchite is associated with cerussite and anglesite, white pyromorphite, libethinite, and sampleite. It forms part of an unusual suite of secondary cadmium-bearing minerals including goldquarryite, niedermayerite, and otavite and the recently described nyholmite and edwardsite (Elliott et al. 2009; Elliot, Brugger, and Caradoc-Davies 2010).

Birchite forms pale blue sprays and aggregates of radiating crystals to 0.75 mm across. It is translucent in masses and transparent as individual crystals, with a vitreous luster, a hardness of 3.5–4 and a calculated density of 3.647 g/cm3. Birchite is brittle and shows conchoidal fracture. It is orthorhombic, space group Pnma. The type specimen is preserved in the Department of Mineralogy, South Australian Museum, Adelaide.

Dermot A. Henry is manager of the natural science collections at Museum Victoria in Melbourne and is also editor of the Australian Journal of Mineralogy.

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