Puttapaite, Pb2Mn2+2ZnCr3+4O2(AsO4)4(OH)6·12H2O, is a new mineral from the Beltana deposit, Puttapa, Flinders Ranges, South Australia, Australia. It forms rosette-like aggregates to 50 micrometers across composed of diamond-shaped tablets to 45 micrometers in length and 5 micrometers in thickness. Crystals are flattened on {001} and the observed forms are {001} and {110}. The calculated density is 3.562 g/cm–3. Optically, puttapaite is biaxial (−) with α = 1.700(5), β = 1.720(5), γ = 1.730(5) and 2V (meas.) = 67(1)°. Electron microprobe analyses gave the empirical formula (based on 36 oxygen atoms pfu) Pb1.96(Mn2+1.52Ca0.28Sr0.22)Σ2.02(Zn0.40Mg0.39Cu0.15)Σ0.94(Cr3+2.89Al0.45Fe3+0.40,Mn3+0.26)Σ4.00O2[(AsO4)3.71(Cr6+O4)0.29]Σ4.00(OH)6.13·11.87H2O. Puttapaite is monoclinic, C2/m, with a = 12.405(3), b = 10.565(2), c = 12.311(3) Å, β = 106.06(3)°, V = 1550.4(6) Å3 and Z = 2.

The structure was solved using synchrotron single-crystal X-ray diffraction data and refined to R1 = 0.1189 on the basis of 915 observed reflections with F0 > 4σ(F0). Puttapaite has a unique structure that consists of M4O16 clusters that share corners with TO4 tetrahedra, which in turn share corners with M1 octahedra in the [010] direction. Clusters link in the [001] direction via corner sharing M2 octahedra to form sheets parallel to {100}. Pb anions lie between the sheets.