Wooldridgeite, Na2CaCu22+(P2O7)(2)(H2O)(10): A new mineral from Judkins quarry, Warwickshire, England

Wooldridgeite, ideally Na2CaCu22+(P2O7)(2)(H2O)(10), orthorhombic, a = 11.9 38(1), b = 32.854(2), c = 11.017(1) Angstrom, V = 4321.2(8) Angstrom(3), a: b:c = 0.3634:1:0.3353, space group Fdd2. Z = 8, is a new mineral from Judki ns Quarry, Nuneaton, Warwickshire, England. Associated minerals are calcite , chalcopyrite, bornite and baryte. It occurs as equant crystals forming rh ombic dipyramids; no twinning was observed. It is transparent blue-green wi th a very pale-blue streak, a vitreous lustre, and does nor fluoresce under long- or short-wave ultraviolet light. Wooldridgeite has a Mohs hardness o f 2-3, is brittle with an irregular fracture, and has no cleavage. The calc ulated density is 2.279 g/cm(3). In transmitted light, wooldridgeite is col ourless, non-pleochroic, and shows no dispersion. It is biaxial negative wi th alpha = 1.508(1), beta = 1.511(1), gamma = 1.517(1), 2V(meas.) = 76.2(5) , 2V(calc.) = 71(10)degrees, X = b, Y = c, Z = a. The strongest five reflec tions in the X-ray powder diffraction pattern are [d(Angstrom), (I), (hkl)] : 8.23(30)(040), 6.52(100)(131), 4.05(40)(260), 3.255(40)(262); 2.924(40)(3 71). 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 w t.%; the corresponding unit formula (based on 24 anions) is (Na1.96K0.03)Ca -1.00(Cu1.85Mg0.04)P4.04O14(H2O)(10) where the H2O groups were assigned fro m knowledge of the crystal structure; the infrared absorption spectrum also indicates the presence of H2O in the structure. The mineral is named fur J ames Wooldridge (1923-1995), a fervent amateur mineral collector who discov ered this mineral.