Airdite, Sr(V4+O)2(PO4)2·4H2O, a New Mineral from the Spring Creek Copper Mine, South Australia, Australia

Abstract Airdite, Sr(V4+O)2(PO4)2·4H2O, is a new mineral from the Spring Creek copper mine, South Australia, Australia. It has crystallized from low-temperature hydrothermal solutions in small cavities in quartz veins. Airdite forms thin platy crystals up to 80 μm in length and crystal clusters up to 0.5 mm across. It is transparent, pale green, with vitreous luster. The mineral is brittle, with excellent {001} cleavage. The Mohs hardness is about 3. The calculated density is 3.116 g/cm−3. Airdite is optically biaxial (−), α = 1.690(2), β = 1.696(2), γ = 1.696(2), and 2Vcalc = 0°. Electron-microprobe analyses gave the empirical formula, based on 32 O apfu, (Sr0.46Ca0.25Ba0.23)Σ0.94(V4+1.94Fe3+0.03Cu0.02)Σ1.99(P2.02O4)O10H8.13. Airdite is monoclinic, space group Cc, a = 9.0060(18), b = 8.9914(18), c = 12.796(3) Å, β = 100.25(3)°, V = 1019.7(4) Å3, and Z = 4. The crystal structure was solved from synchrotron single-crystal diffraction data and refined to R1 = 6.00% for 2380 reflections with F0 > 4σ(F0). The structure is based on autunite-type sheets of vertex-sharing VO6 octahedra and PO4 tetrahedra. Strontium cations are located in the intersheet region.