Stibnite Vein from Dębowina Near Bardo (Polish Sudetes)

28 Contemporary Trends in Geoscience vol . 2 DOI: 10.2478/ctg-2014-0004

Piotr Kotula Stibnite vein from Dębowina near Bardo Faculty of Earth Science, University of Silesia, Bedzinska Str. 60, 41-200 Sosnowiec. (polish Sudetes) E-mail: [email protected]

Keywords: Abstract. Bardo Structure, stibnite, Ag- In the contact zone of the Bardo Structure rich in Mn. Stibnite crystallizes as columnar deposit, old mines, propy- and Kłodzko-Złoty Stok Intrusion and or forming radiate centres and aciculars. Its litic, SEM. Kłodzko Metamorphic, metasomatic ore- crystals reach size to 2 mm. Sphalerite ap- bearing quartz-carbonate veins rich in Sb, pears as individual anhedral and polyminer- Zn, Cu, Ag, Au, Pb are present. In 1771 the alic grained concentrations reaching size to mine ,,Reiche Silber Glück” within stibnite 2,5 mm. Earlier pyrite and arsenopyrite crys- vein was founded in Dębowina near Bardo. tallized – they occur locally in this deposit. Its entrance was discovered again in 2007. There were found also in the deposit tetra- The stibnite vein is mainly build of stibnite hedrite rich in Ag, what wasn't reported ear- and sphalerite and of quartz and dolomite lier in studies from the mine in Dębowina. Contemporary trends in Geoscience vol . 2 29

Introduction Stibnite-quartz vein and quartz-carbonate bring profits. It worked to the end of 18 cen- veins occur in terranes dominated by meta- tury (Dziekoński 1972). Later it was the ob- sedimentary sequences, for example in a ject studied by geologists and mineralogists lot of places all over the world e.g. Alaska, (Mączka and Stysz 2008). Petrascheck (1933) Canada, Europe (Neiva et al. 2008). Quartz- described that place as ore-rich with pyrite, carbonate veins rich in Sb, Zn, Cu, Ag, Au, zinc blende, arsenopyrite, galena, stibnite Pb in Dębowina were studied by Kaluza in and chalcopyrite. He examined that ore ap- 1818, Fechner in 1901 and Petrascheck in 1933 peared with pyrite and calcite in diorites or (Lis and Sylwestrzak 1986). The author of this syenites which are an overlay and metagrey- paper introduces review of minerals from wackes. It can be distinguished two types an- ,,Reiche Silber Glück” mine in Dębowina timony-bearing ores: within igneous intru- near Bardo. Silver mine originated in 1771, sions and in metagreywackes. The old mine three years after miners founded the compa- was inaccessible and forgotten for a long time, ny eg. ,,gwarectwo” (Mączka and Stysz 2008). but in 2007 it was discovered again (Mączka The mine did not work constantly and did not and Stysz 2008).

Geological setting The object of investigations is the ,,Reiche places cut by igneous rocks – diorites or sy- Silber Glück” mine located about 400 me- enites. Porphyry rocks are genetically re- ters SW from the Bardo Pass (Fig 1). Bardo lated to Variscan orogeny (Mikulski 1998). Pass is located within Bardo Structure and Porphyry deposits from near the end of a Kłodzko-Złoty Stok Intrusion. magmatic episode or during a change of de- Rocks of that structure consist of Upper formation styles when the arc is undergo- Devonian and Lower Carboniferous grey- ing limited contraction (Sillitoe 2000). In wacke sandstone, mudstone and pudding many parts of the Variscan orogenic belt, stone, which are covered with quaternary quartz vein mineralization is related to the boulder clay. Sedimentary rocks are in many influx of deep-sourced fluids during late- orogenic exhumation Sb, Zn Cu, Ag, Pb ore and had been extracted from Paleozoic sedimentary sequences (Wagner&Cook 1998, Wagner&Cook 2000). Propylically altered of fragmental porphyry induced ore precipitation within vein. Therefore in intrusions appear propylitic metasomatic mineraliza- tions rich in sulfides of Sb, Zn, Cu, Ag, Fe, Pb, Au. The ,,Reiche Silber Glück” mine is located in one this intrusions. The origin of stibnite-bearing vein in Dębowina is not pre- cisely defined.

Fig 1. Simplified geological sketch of the Bardo Structure with location of the old mine in Dębowina (after Kryza et al. 2011). 30 Contemporary Trends in Geoscience vol . 2

Samples and methods The author collected 8 samples containing on a scanning electron microscopy (SEM) sulfides metals. One of them is a intrusion in Laboratory of Scanning Microscopy at rock. Other samples are strongly weather- Faculty of Earth Sciences, University of Silesia ing greywackes. Rocks and sulfide miner- with use of environmental analytical micro- als are mostly located inside the mine. Two scope Philips ESEM XL30/TMP with attach- samples were studied. Polished sections were ment EDS (Energy Dispersive Spectrometer)/ studied by microscope methods reflected EDX Sapphire type in low-voltage regime and light. After that ore minerals were analyzed low-vacuum.

Results Microscopic and SEM studies allowed to radiate needles, white and grey, with high classify the stibnite-bearing veins from reflectance (fig 2a.). Stibnite crystals reach Dębowina as Sb – Zn – Ag deposit. Main to 2 mm. Sphalerite appears as individual minerals components in that vein are quartz, anhedral cristals. Sphalerit cristals reach to carbonate, stibnite and sphalerite. EDS spec- 2,5 mm (fig 3b.) Pyrite and arsenopyrite ap- trum of carbonate shows high concentration pear seldom. The amounts of pyrite and ar- of manganese (fig 4b.). Quartz and MN-rich senopyrite increase on perimeter of the vein. dolomite makes up more than 25 vol% of Isomorphic crystals of these minerals get the vein. In generally, coarse-grained stib- stuck in quartz and they have typical opti- nite and sphalerite are dominated (fig 2a.). cal features (fig 2b. and fig 3a.). Stibnite occurs as columnar cristals and

Fig 2a. Minerals of stibnite-bearing vein from Dębowina in reflected light: Stb – stibnite, Sph – sphalerite. 1 nicol.

Fig 2b. Minerals of stibnite-bearing vein from Dębowina in reflected light: Stb – stibnite, Sph – sphalerite, Py – pyrite, Qtz – quartz. 1 nicol. Contemporary trends in Geoscience vol . 2 Piotr Kotula 31

Stibnite vein from Dębowina near Bardo (polish Sudetes)

Fig 2c. Minerals of stibnite-bearing vein from Dębowina in reflected light: Sph – sphalerite, Tet – tetrahedrit. 1 nicol.

Fig 3a. SEM images of stibnite with as- sociated minerals. Asp – arsenopyrite, Qtz – quartz.

Fig 3b. SEM images of stibnite with as- sociated minerals. Stb – stibnite, Sph – sphalerite, Crb-Mn – dolomite rich in Mn, Py – pyrite, Qtz – quartz.

Fig 3c. SEM images of stibnite with as- sociated minerals. Stb – stibnite, Sph – sphalerite, Crb-Mn –dolomite rich in Mn, Tet – tetrahedrite rich Ag. 32 Contemporary Trends in Geoscience vol . 2

In the studied deposit isomorphic pyrite and its chemical composition shows that it is Ag- arsenopyrite are the earliest sulfides to form. tetrahedrite (fig 4c.). In the centre of vein The author discovered in analyzed vein Ag- there are sphalerite and stibnite. In medium tetrahedrite, which is accessory minerals in part of vein appear tetraedrite, pyrite and ar- it (fig 3c.). It hasn't got typical, characteris- senopyrite. The outer layer there are mainly tic colour and optical features (lower reflect- quartz and carbonates with rare arsenopy- ed), but is isotropic (fig 2c.). EDS spectrum rite found out (fig 3a.).

Fig 4a. EDS spectrum of stibnite. Fig 4b. EDS spectrum of Mn-dolomite Fig 4c. EDS spectrum of Ag-tetrahedrite.

Conclusions The main components in stibnite-bearing antimony before precipitation sulfides of Sb- vein are stibnite and sphalerite. In the stib- Zn-Ag-Cu (Grancea et al. 2002). The author nite-bearing vein accessories appear pyrite in studied material haven't found gold and and arsenopyrite. In general, arsenopyrite sulfide of Au. However there is a possibility, and pyrite are the earliest sulfides and stib- that gold in the mine in Dębowina not only is nite, sphalerite are late sulfides. The author dispersed in other minerals, but it forms indi- describes tetrahedrite rich in Ag, which is ac- vidual minerals. The studied place is unique, cessory mineral in vein, but it has never been because its role in local mining industry. described in Dębowina region. Experimental Future studies will focus on stable isotopes studies, with increasing Ph, a Sb-complex is analyzes of carbon and oxygen in Mn-rich formed, as shown in this reaction (Krupp dolomite, in order to describe an origin of 1988): vein with stibnite and sphalerite. Carbonates ½ Sb2S3 + ½ H2S <--> ½ Sb2S42- + H+ will be chemically prepared for the determi- As a consequence, tetrahedrite or other nation of C and O isotopic data at the Silesian sulphosalts prevail over stibnite in the Sb- University of Technology, Institute of Physics bearing deposit. Tetrahedrite replaced by Gliwice Radiocarbon Laboratory (Poland). stibnite reflect differentiation of polymetal- Ratios 13C/12C and 18O/16O depend on or- lic fluids in course of vein formation. igin of carbon and oxygen in metasomatic Probably the abundance of sulfide or sulpho- fluids (Schwarcz&Burnie 1973). salts minerals is larger than described before, manly by Petraschecka (1933). The char- acteristic feature in antimony-bearing ore is high concentration of Mn in carbonates. Carbonates rich in Mn (for example kutno- horite or rhodochrozite in the Baia Mare, Romania) crystallized in other deposits of Contemporary trends in Geoscience vol . 2 Piotr Kotula 33

Stibnite vein from Dębowina near Bardo (polish Sudetes)

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