The crystal structure of kintoreite, PbFe3(PO4)2(OH,H2O)6, has been refined. The mineral is rhombohedral, Rm with a = 7.3310(7), c = 16.885(2) Å, Z = 3; the structure has been refined to R = 3.0% and Rw = 3.0% using 183 observed reflections [I > 2σ(I)]. Kintoreite has the alunite-type structure which consists of sheets of corner-sharing Fe(O,OH)6 octahedra parallel to (001). The sheets are composed of clusters of three corner-linked octahedra which are tilted so that the three apical O atoms form the base of the XO4 tetrahedra. The clusters of octahedra are linked to similar groups by corner-sharing to form six membered rings. The Pb cations occupy the cavities between pairs of octahedral sheets and are surrounded by six oxygen atoms from the tetrahedra and six oxygen atoms from the octahedra to form a very distorted icosahedron. The mean bond lengths for the various coordination polyhedra are X–O 1.55 Å, (X= P, As, S); Fe–(O, OH) 2.01 Å; Pb–O 2.84 Å. The composition of the crystal used in the refinement was PbFe3(PO4)1.3(AsO4)0.4(SO4)0.3(OH,H2O)6. The XO4 anions are disordered, as in beudantite, rather than being ordered, as they are claimed to be in corkite.

The profile of the supergene zone of the Zapadno-Ozernoe massive sulphide Cu-Zn deposit differs from the classic model (Emmons, 1917) in that it includes a prominent dark sooty subzone rich in secondary sulphides. This subzone is situated above residual pyrite sands, which overlie the massive sulphide body and below quartz-baryte leached sands. It contains a diverse mineral assemblage which consists of secondary sulphides such as galena, sphalerite, metacinnabar, Se-bearing pyrite—dhzarkenite series, tiemannite, native Au, native S and native Se, and unidentified sulphosalts of Ag and Hg. The very light S isotope composition of the secondary sulphides (lowest values δ34S = —17.2‰ (VCDt) in comparison with primary pyrite ∼0‰ and baryte +18.4‰ is indicative of bacterial sulphate reduction. The overlying oxidized part of the supergene column contains minerals of the jarosite-beudantite- segnitite series. The maximum concentrations of Au, up to 150 ppm, occur in the lower part of the profile. The atypical structure, mineral assemblage and S isotope composition of the secondary sulphides in the dark layer of the supergene profile are indicative of particular geochemical conditions due to the existence of a stagnant water body that gave rise to intense bacterial activity, in turn controlled by fluctuations in the redox boundary.