COMPOUNDS WITH MIXED AND INTERMEDIATE SULFUR VALENCES AS PRECURSORS OF BANDED SULFIDES IN CARBONATE-HOSTED ZN-PB DEPOSITS IN BELGIUM AND POLAND

Compounds of Fe, Pb and Zn with mixed and intermediate sulfur valences form ubiquitous inclusions and relics in banded sphalerite, pyrite-melnikovite and galena. Banded sulfides continuously grade into banded compounds with mixed and intermediate sulfur valences, the latter with a fibrous microtexture. A fibrous microtexture is also shown by banded sphalerite and pyrite from Zn-Pb deposits of Belgium and Poland. It is therefore suggested that the fibrous sphalerite inherited such a microtexture, unusual for cubic ZnS, by direct replacement of a fibrous precursor with mixed and/or intermediate sulfur valences. The last band of banded sphalerite is often overgrown by idiomorphic, isometric sphalerite precipitated directly from the solution as ZnS. The following Fe, Pb and Zn compounds with mixed and intermediate sulfur valences were found in carbonate-hosted Zn-Pb deposits of Belgium and Poland: sulfoxylanes (M2+SO,; S2+), subsulfites (M2+S2O4; S3+), sulfites (M2+SO3; S4+), pyrosulfites (M2+S2O5; S4+) and thiosulphates (M2+S2O3; S2- and S6+).