Obradovicite, ideal formula H4CuFe2(AsO4) (MoO4)5 · 12H2O, occurs as fine pea-green clusters on quartz from Chuquicamata, Chile. Obradovicite is orthorhombic, space group Pcnm; a = 15.046, b = 14.848, c = 11.056 Å, Z = 4. The strongest powder pattern lines are (d Å, I, hkl) 10.565(8)(110), 8.906(10)(101), 7.424(8)(020), 5.733(5)(211), 3.761(3)(400), 3.686(4)(032), 3.466(3)(411), 3.344(4)(420). It is biaxial positive with α = 1.790, β = 1.798, γ = 1.811, 2Vz = 81°, a = Z, b = X, c = Y, with strong dispersion and pale yellow pleochroism. Specific gravity is 3.55 (meas.) or 3.68 (calc.) and the Mohs hardness is 2½ with no obvious cleavage. Obradovicite is similar to betpakdalite and sodium-betpakdalite except that it contains essential Cu and K (K > Na).

Cu2Th4(MoO4)9 is cubic: a=14.4856(1) Å, space group I4¯3d, Z=4. Its crystal structure was recently determined using a single crystal. The results of chemical study allow one to reject the existence of Li4Th7(MO4)16 and La(MO4)(ReO4) compounds with M=Mo, W, reported as isostructural with Cu2Th4(MoO4)9. Precise X-ray powder patterns are established for Cu2Th4(MoO4)9 and isotypic compounds Li2Th4(MoO4)9, Li2Th4(WO4)9, and La4(MoO4)3(ReO4)6.