Natural orthorhombic sulfur (α-S8), grown on galena crystals from Cap Garonne, Mine du Pradet, France, were studied by single crystal X-ray diffraction at 150 K: Fddd, a=1036.75(5), b=1273.54(7), c=2437.85(13) pm, wR=0.0380, 1433 F2 values (all data) and 37 variables. Refinements of the occupancy parameters along with EDX data indicate pure sulfur.
Natural lead dioxide samples (β modification) from Cap Garonne, Mine du Pradet, France and Mount Trevasco, Italy were studied by single crystal X-ray and electron diffraction, clearly manifesting the rutile-type structure. A needle from the Mount Trevasco sample was investigated on a single crystal diffractometer: P42/mnm, a = 495.81(10), c = 338.66(7) pm, wR = 0.0513, 117 F2 values (all data) and nine variables (293 K data). An additional data set at T = 90 K gave no hint for structural distortions.
Linarite, PbCuSO4(OH)2, crystallizes as secondary mineral in form of clusters of crystals in Mine du Pradet at Cap Garonne in France. A tiny single crystal was isolated and its structure was refined from synchrotron diffraction data (λ = 0.049592 nm): P121/m1, a = 467.75(2), b = 563.48(4), c = 967.64(5) pm, β = 102.647(5)°, wR = 0.0544, 819 F 2 values and 56 variables. The proton positions were also refined. The Cu2+ cations are located within Cu(OH)2 ribbons and exhibit pronounced Jahn-Teller distortion (d(Cu–O): 2 × 191.9, 2 × 197.3 and 2 × 252.8 pm). The Cu(OH)2 ribbons are condensed with the sulfate tetrahedra and the lead cations. The latter are coordinated to eight oxygen atoms in a slightly anisotropic manner. Calculations of the electron localization function (ELF) of PbO (litharge), PbSO4 (anglesite) and PbCuSO4(OH)2 (linarite) show pronounced lone-pair character for PbO but rather isotropic ELF values around the lead cations in PbSO4 and PbCuSO4(OH)2.
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