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Banska Stiavnica |
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Slovak Republic |
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Au Ag Pb Zn
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Super Porphyry Cu and Au
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The Banska Stiavnica Au-Ag-base metals, epithermal deposit is located in southern-central Slovakia (Slovak Republic), within the western Carpathians Neogene neovolcanic belt.
It has been mined for Ag, Au, Pb, Zn & Cu since the 8th century and has yielded >100 tonnes of Au and 1500 to 2000 t of Ag. Proven reserves in 1999 were 1.5 Mt @ 2.2% Pb, 3.2% Zn, 42 g/t Ag, 4.8 g/t Au, while probable reserves are of the order of 47 Mt.
The deposit occurs within a concentrically zoned volcanic caldera complex in which an early Miocene granodiorite-quartz diorite pluton has intruded pre-Cenozoic sediments, with associated magmatic andesites and rhyolite lavas. The intrusives have been variously dated at 17 to 16 Ma and 13 to 11 Ma, while the rhyolite lavas are 11.6 ±0.3 Ma.
The first phase of pre-caldera hydrothermal mineralisation comprised stockwork-disseminated base metals with advanced argillic alteration and was associated with the intrusion of quartz-diorite porphyries and granodiorite.
Post caldera hydrothermal systems are represented by 16 to 11 Ma quartz and quartz-carbonate veins with precious and base metal mineralisation accompanied by linear zones of quartz-carbonate-sericite alteration. The economic mineralisation is temporally related to this second phase and numerous quartz-diorite porphyry dykes that occur along the margin of the intrusive granodiorite stock in the central part of the caldera.
Ore is present in around 120 quartz-carbonate veins, each 0.8 up to 10 to 15 m in thickness, that extend over strike lengths of 5 to 7 km and vertical interval of 700 to 900 m. Four main mineralisation zones are recognised from bottom to top, as follows: 1). Cu zone, 2). lower Pb-Zn zone, 3). upper Pb-Zn zone, and 4). the uppermost Au-Ag zone. The mineral paragenesis has been determined to comprise: a). quartz-hematite, b). sphalerite, c). rhodonite-carbonate-quartz, d). galena-chalcopyrite, and e). Ag bearing sulfosalt-barite. Economic grades accompanied stages b), d), and e).
For detail consult the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 2000.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Selected References:
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Prokofiev V, Kamenetsky V S, Kovalenker V, Bodon S B, Jelen S 1999 - Evolution of magmatic fluids at the Banska Stiavnica precious and base metal deposit, Slovakia - evidence from melt and fluid inclusions: in Econ. Geol. v94 pp 949-956
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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