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Zdzisław Migaszewski and Agnieszka Gałuszka

The 1st Conference on Contemporary Problems of Geochemistry

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Zdzisław Migaszewski and Agnieszka Gałuszka

Xenotime from the Podwiśniówka mine pit, Holy Cross Mountains (South-Central Poland)

This report presents the results of petrographical and mineralogical (optical microscopy, SEM/EDS) study of xenotime derived from the Upper (Middle?) Cambrian rocks (Wiśniówka Sandstone Fm.) of the abandoned Podwiśniówka mine pit. This is the first work on this mineral from the Holy Cross Mts. The authigenic xenotime occurs primarily as overgrowths around/on zircon in siliciclastic rocks. Moreover, this mineral is characterized by the large size of the overgrowths reaching 50 μm long and 20 μm wide. The presence of pyritecoated zircon/xenotime aggregates indicates that the xenotime formed prior to hydrothermal quartz-pyrite mineralization. The apparent lack of xenotime and vein pyrite in the tuff-bearing series, compared to the other two series displaying hydrothermal signature (pyrite, hematite, nacrite, jarosite), as well as considerable variations of the xenotime overgrowths in size and morphology, and their dominant irregular patchy-zonal microtexture may provide evidence for direct precipitation of this mineral from hydrothermal fluids.

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Agnieszka Gałuszka and Zdzisław Migaszewski

Geochemical background - an environmental perspective

This article presents the concept of geochemical background from an environmental perspective. The idea of establishing the typical concentrations of elements in various environmental compartments, proposed by exploratory geochemists almost 50 years ago was important for the detection of anomalous element concentrations, thus providing a basic tool in the search for new mineral deposits. At present, the knowledge of the geochemical background of hazardous elements is essential for: defining pollution, identifying the source of contamination, and for establishing reliable environmental quality criteria for soils, sediments and surface waters. The article presents geochemical methods of evaluation of anthropogenic influence on the environment and discusses the problem of defining and understanding the term "geochemical background" and related terms in environmental sciences. It also briefly presents methods of geochemical background evaluation based on the results of environmental sample analyses. It stresses the role of geochemical background in our understanding of environmental pollution and pollution prevention.

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Zdzisław Migaszewski, Ewa Starnawska and Agnieszka Gałuszka

Gorceixite from the Upper Cambrian Rocks of the podwiśniówka Mine Pit, Holy Cross Mountains (South-Central Poland)

This report presents the results of a petrographical, mineralogical (SEM/EDS, XRD) and geochemical (XRF, CV-AAS, ICP-MS) study of gorceixite (barium aluminophosphate) from the abandoned Podwiśniówka mine pit. This site is highlighted by the presence of highly acidic pit pond whose chemistry is strongly affected by the exposed pyrite-bearing zone. The gorceixite occurs in the Upper Cambrian carbonaceous clayey shales, quartzites and tuffs in form of minute accumulations varying from about 0.5 to 100 μm in diameter. These accumulations infill voids, cavities, cracks and partly fissures in the rocks examined. The other minerals of the crandallite series, i.e. florencite and goyazite, can be found only in trace amounts. The gorceixite-bearing rocks, especially carbonaceous clayey shales, are characterized by the highest concentrations of REE reaching 455.09 mg·kg-1. In addition, these rocks are distinctly enriched in light rare earth elements (LREE), with the La/Yb ratio ranging from 24.44 through 36.30. Some of the examined gorceixite accumulations are paragenetically linked to the veined pyrite and nacrite. The latter mineral is indicative of crystallization temperatures of about 200 to 300°C. The coexistence of gorceixite with the veined nacrite or pyrite mineralization and the volcaniclastic rocks, as well as the microtextural features and high concentrations of REE in the gorceixite-bearing parent rocks suggest that this mineral formed as a result of both hydrothermal and volcanic activity in a shallow-marine basin during the late Cambrian.