A physical and chemical description of a scrubber dust slurry, known as Theisenschlamm, is presented. This material is generated as a by-product during extraction of copper from a mineralized Permian black shale (Kupferschiefer) in Sachsen-Anhalt, Germany. The Theisenschlamm consists of sulphide grains which are a complex solid solution of Pb, Zn, Cu and Fe. The crystal structures are modified forms of galena and sphalerite/wurtzite. Variations in the X-ray diffraction peak positions of these minerals reflect the poorly developed lattice structures of these phases. Anglesite is a secondary phase. The Theisenschlamm contains 18% Zn and 14% Pb as well as significant concentrations of PAH, PCDD and other organic compounds, rare metals and radionuclides (e.g. ²¹⁰Po and ²¹⁰Pb). The original particles have a median diameter of 1.25 μm, however, these particles are themselves aggregates of still smaller particles, typically of submicron size.