Original paper

Mineralogy of the U - Se-polymetallic deposit Niederschlema-Alberoda, Erzgebirge, Germany. IV. The continuous clausthalite-galena solid-solution series

Förster, H.-J.

Abstract

In a sample from the Niederschlema–Alberoda U–Se-polymetallic deposit, western Erzgebirge, Germany, the entire PbSe–PbS solid-solution series was observed associated with uraninite, coffinite, hematite, acanthite, sphalerite, chalcopyrite, pyrite, and löllingite. Early deposited, Se-rich members of the Pb(Se,S) series occur as fracture fillings inside spherical uraninite or on its surface or form anhedral to subhedral grains precipitated in the immediate neighbourhood of the U minerals. Later crystallized, S-rich members of the series are affiliated with the sulfide minerals. The solid-solution series covers the range PbS1.00–Pb(S0.04Se0.96)σ1.00 virtually free of gaps, consistent with a temperature of formation of ≥ 100 °C. The PbSe – PbS solid solutions were likely deposited from hydrothermal fluids that became successively depleted in Se and enriched in S. The fugacities of selenium and sulfur covered the range–17 < logƒse2 < - 26 and -17

Keywords

clausthalitegalenanaumanniteacanthitesolid-solution seriesmiscibilityselenium mineralsuranium depositerzgebirge