Noble metals in organic matter and clay-organic matrices, Kupferschiefer, Poland

In the Kupferschiefer deposits of Poland, Cu, Ag, Pb, Zn, Fe, noble metals, and other transition elements were concentrated by a process of catalytic oxidation and desulfurization of organic matter. They occur as several well -defined horizons that are zoned from the bottom upward: noble metals (sout hwest perimeter of ore bodies), Cu, Pb, Zn, and pyrite. The noble metal content in black shale clay-organic matrices reaches 1,900 ppm Au, 1,900 ppm Pd, and 600 ppm Pt. Gold valence determinations suggest t hat Au occurs in two forms: native microinclusions with 0 valence containin g silver, and Ag-free microinclusions with gold valence +1 probably bound t o bitumens. The noble metals content in the organic matrix of thucholite re aches 2,528 ppm Au, 5,000 ppm Pd, and 1,770 ppm Pt. Pt is probably bound to tetrapyrrole rings, with Ni and V as vanadyl. The vertical distribution of metals is controlled by redox interfaces. On t he reduced side of the interface, up to 0.5 m thick, the following minerals occur: a continuous Ag-Au series, several Pd arsenides and sulfide-arsenid es, Pi sulfides, tennantite, Co-Ni arsenides, castaingite CuMo2S5, thucholi te, covellite, and digenite. On the oxidized side of the interface, up to 1 m thick, the following minerals occur: gold of high fineness, hematite, Pd Bi sobolevskite, clausthalite, native Pb, plumbian gold, native palladium, graphite, and relicts of organic matter. The oxidized portion of the redox interface, containing lower noble metal contents, occupies a much larger ar ea than the reduced counterpart with its higher pay metals values.