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Recently formed arsenates from an abandoned mine in Radzimowice (SW Poland) and the conditions of their formation

Siuda Rafał, Januszewska Anna

Acta Geologica Polonica

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2022

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Vol. 72, no. 4

423--442

EN

In the mining galleries of the abandoned Au-As mine in Radzimowice, diverse groups of secondary arsenates crystallized recently. They form several characteristic assemblages. In the first of them the typical minerals are bukovskýite and melanterite. The second group of secondary arsenates includes scorodite, kaňkite, zýkaite, and pitticite. The third assemblage includes Co-Ni-Mg arsenates of the erythrite-annabergite-hörnesite series. The first assemblage crystallized in a zone with a very high activity of sulphate and arsenate ions and where the pH varies within a narrow range of 2.0-3.5. The second group of secondary arsenates formed in the acidic zone. The minerals identified here suggest pH variation within fairly wide ranges, from about 2.0 to 5.5. Contrary to the first and second mineral assemblage, the Co-Ni-Mg arsenates formed under different geochemical conditions. Their crystallization took place under weak acidic to neutral conditions.

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Recently formed secondary copper minerals as indicators of geochemical conditions in an abandoned mine in Radzimowice (SW Poland)

Siuda R., Kruszewski Ł.

Geological Quarterly

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2013

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Vol. 57, No. 4

583–-600

EN

An occurrence of twelve recently formed secondary copper minerals (SCM) was observed in underground workings of an abandoned Cu-As-Au mine in Radzimowice. The minerals, mainly sulphate species, were identified using Powder X-Ray Diffraction (PXRD), scanning electron microscope with energy dispersive spectroscopy system (SEM-EDS) and electron microprobe analysis with wavelength-dispersive spectrometry system (EPMA-WDS) methods. The SCM of Radzimowice form the following assemblages: paragenesis I is characterized by langite, posnjakite, brochantite and devilline. These minerals crystallise directly from pH 6.0–7.0 mine waters. Paragenesis II also comprises hydrous copper sulphates (HCS), and in addition contains native copper, cuprite, ferrihydrite and gypsum. Secondary HCS mainly crystallise as products of reactions of sulphate-rich mine waters with native copper and cuprite. The pH of these waters varies from ~5.0 to 6.0. The III paragenesis is dominated by woodwardite, associated with variable amounts of chalcoalumite and amorphous Cu-Al sulphates. Accumulations of woodwardite occur in the zones where Al- and sulphate-rich acid mine waters (pH ~2.5–3.0) mix with neutral waters (pH 6.5–7.0). Paragenesis IV is rare, dominated by chrysocolla, coexisting with small amounts of mottramite and goethite. This assemblage formed as a result of mobilization of silica released during decomposition of rock-forming aluminosilicates attacked by acid mine waters

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Paragenezy hipergeniczne złoża Radzimowice (Góry Kaczawskie)

Siuda R.

Przegląd Geologiczny

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2012

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Vol. 60, nr 8

442--449

EN

The polymetallic Radzimowice deposit is located in the vicinity ofRadzimowice 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 andPb, 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. Kankite, scorodite and zykaite are the most widespread constituents of this assemblage. Large accumulations ofpitticite, 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 ofthese phases can result in the release ofarsenic and heavy metals into the groundwater and in the migration ofthese elements into the environment.