ARTYKUŁY NAUKOWE Paragenezy hipergeniczne złoża Radzimowice (Góry Kaczawskie)

Rafał Siuda


Supergene parageneses of the Radzimowice deposit (Kaczawa Mts., Poland).
A b s t r a c t. The polymetallic Radzimowice deposit is located in the vicinity of Radzimowice village, about 20 km east of Jelenia Góra (Western Sudetes, Poland). The deposit consists of several ore veins. The primary ore assemblage is represented by arsenopyrite, pyrite and chalcopyrite, and less common galena, sphalerite, Cu-Pb-Sb sulphosalts of Cu and Pb, and native gold. The mining activity in this area started in the mid-12th century and lasted until the mid-20th century. This paper presents general information about typical parageneses of secondary minerals occurring in the oxidation zone of the Radzimowice deposit. Based on the mineralogical investigations, 43 secondary mineral species have been recognized. Such a rich assemblage of secondary minerals makes the oxidation zone one of the most interesting formations of this kind in Poland. Phosphates (pseudomalachite, phosphosiderite) and sulphides (covellite, chalcocite) of copper were ascertained in the near-surface part of the supergene zone. Secondary lead minerals (cerussite, pyromorphite and mimetite) were found only in medieval dumps. Phosphates and sulphides
of Cu and supergene lead minerals belong to sub-recent secondary parageneses. Since the end of local mining activity in 1957, the intensive weathering processes caused the decomposition of ore minerals in the mine galleries, producing recently forming associations of new minerals. The first mineral paragenesis is represented by recently formed arsenates. Kaòkite, scorodite and zýkaite are the most widespread constituents of this assemblage. Large accumulations of pitticite, forming stalagmites up to 10 cm in length,
are sometimes found in old mine galleries. In those parts of the abandoned mine, where pyrite is a dominant primary mineral, huge accumulations of the minerals related to acid mine drainage are present. Schwertmannite, ferrihydrite and poorly crystalline goethite are the main representatives of this paragenesis. Associations of basic copper sulphates are present in all parts of the abandoned mine. Langite, posnjakite, brochantite and devilline are the most common minerals of this assemblage. Sulphates of Cu and Al
(chalcoalumite and cyanotrichite), native copper, cuprite and malachite are locally found to coexist with these phases. Precipitations of secondary minerals play an important role in the retention and liberation of considerable amounts of toxic elements. Dissolution of these phases can result in the release of arsenic and heavy metals into the groundwater and in the migration of these elements into the environment.

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