Wooldridgeite, Na2CaCu22+(P2O7)2(H2O)10: A New Mineral from Judkins Quarry, Warwickshire, England

F. C. Hawthorne, M. A. Cooper, D. I. Green, R. E. Starkey, A. C. Roberts and J. D. Grice
Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada, R3T 2N2
The Manchester Museum, University of Manchester, Oxford Road, Manchester M13 9PL, UK
15 Warwick Avenue, Bromsgrove, Worcestershire B60 2AH, UK
Geological Survery of Canada, 601 Booth Street, Ottawa, Ontario, Canada K1A 0E8
Research Division, Canadian Museum of Nature, PO Box 3443, Station D, Ottawa, Ontario, Canada K1P 6P4

Abstract: Wooldridgeite, ideally Na2CaCu22+(P2O7)2(H2O)10, orthorhombic, a = 11.938(1), b = 32.854(2), c = 11.017(1) Å, V = 4321.2(8) Å3, a:b:c = 0.3634:1:0.3353, space group Fdd2, Z = 8, is a new mineral from Judkins Quarry, Nuneaton, Warwickshire, England. Associated minerals are calcite, chalcopyrite, bornite and baryte. It occurs as equant crystals forming rhombic dipyramids; no twinning was observed. It is transparent blue-green with a very pale-blue streak, a vitreous lustre, and does not fluoresce under long- or short-wave ultraviolet light. Wooldridgeite has a Mohs hardness of 2–3, is brittle with an irregular fracture, and has no cleavage. The calculated density is 2.279 g/cm3. In transmitted light, wooldridgeite is colourless, non-pleochroic, and shows no dispersion. It is biaxial negative with α = 1.508(1), β = 1.511(1), γ = 1.517(1), 2V(meas.) = 76.2(5), 2V(calc.) = 71(10)°, X = b, Y = c, Z = a. The strongest five reflections in the X-ray powder diffraction pattern are [d(Å), (I), (hkl)]: 8.23(30)(040), 6.52(100)(131), 4.05(40)(260), 3.255(40)(262); 2.924(40)(371). Electron-microprobe analysis of wooldridgeite gave P2O5 39.37, CuO 20.24, MgO 0.24, CaO 7.73, Na2O 8.33, K2O 0.17, H2O(calc.) 24.72, sum 100.80 wt.%; the corresponding unit formula (based on 24 anions) is (Na1.96K0.03)Ca1.00(Cu1.85Mg0.04)P4.04O14(H2O)10 where the H2O groups were assigned from knowledge of the crystal structure; the infrared absorption spectrum also indicates the presence of H2O in the structure. The mineral is named for James Wooldridge (1923–1995), a fervent amateur mineral collector who discovered this mineral.

Keywords: wooldrigeite • new mineral • pyrophosphate • Judkins Quarry • Warwickshire • England

Mineralogical Magazine; February 1999 v. 63; no. 1; p. 13-16; DOI: 10.1180/002646199548268
© 1999, The Mineralogical Society
Mineralogical Society (www.minersoc.org)