Marek Szczerba and Zbigniew Sawłowicz
Remarks on the origin of cerussite in the Upper Silesian Zn-Pb deposits, Poland
Cerussite, the most important oxidized lead mineral in the Upper Silesian Zn-Pb deposits, occurs in two readily distinct types: fine-grained cerussite replacing galena in-situ and macrocrystalline cerussite filling open fractures and cavities. Microscopic observations and thermodynamic considerations lead to the conclusion that galena can be oxidized to lead carbonate directly, not necessarily through an intermediate sulphate phase. Locally present iron sulphides undergoing oxidation acidify solutions and provide ferric ions which are important oxidizing agents. In such microenvironments, anglesite can preferentially form.
Cerussite and galena commonly coexist together with non-oxidized zinc sulphides. It is difficult to explain such assemblages if galvanic couplings made of these two sulphides are not considered. These couplings are only formed when these two sulphides are in direct contact. In such an assemblage, galena undergoes oxidation, mostly to cerussite, and sphalerite is passivated. When there is no direct contact between sulphides, the galvanic couplings do not exist. Galena surfaces become covered by oxidation products which inhibit further oxidation. As such a cover does not form on sphalerite, it can be easily oxidized.
Anna Rogóż, Zbigniew Sawłowicz, Paweł Socha and Krzysztof Stefaniak
Mineralization of teeth and bones of the cave bear (Ursus spelaeus) from the Biśnik Cave, Southern Poland
The studied bones and teeth of the cave bear (Ursus spelaeus) come from the Biśnik Cave, located in the Częstochowa Upland (Southern Poland). The specimens originate from different geological layers formed since the Odra Glaciation (250-270 thousand years BP). The fossilized bones and teeth were studied using optical microscopy, scanning electron microscopy, X-ray diffraction, FTIR spectroscopy, and INAA. They are built of recrystallized carbonate-rich apatite-(CaOH) and/or apatite-(CaOH). The teeth additionally contain some apatite-(CaF). The lack of collagen and minor REE contents suggest rapid burial and collagen decay in the early stage of diagenesis. The bones and teeth have only limited mineral infillings. In some teeth, Mn-Fe (hydroxy)oxides were found in the dentine canaliculi and in bones, some osteocyte lacunae contain Fe (hydroxy)oxides with admixture of Mn. In one bone specimen, calcite infillings are present in Haversian canals. The infillings formed during later stages of diagenesis and were succeeded by non-filled cracks.