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Bratislava, Slovakia

Bonova K.,Ustav Geografie | Bacik P.,Katedra mineralogie a petrologie | Bona J.,kpt. Jarosa 780 13
Bulletin Mineralogicko-Petrologickeho Oddeleni Narodniho Muzea v Praze | Year: 2012

The hexahydrite and ranciéite have been found in travertine or calcareous tufa, respectively in the Vyšné Ružbachy locality. They were identified by the X-ray diffraction methods. Hexahydrite occurs in the thin layers of white colour covering the weathering rocks. Chemical weathering of carbonate rocks is considered to be source of magnesium ions and sulphate can be of Triassic origin. Intergranular sources of carbonates for the soluble magnesium salts are alternatively assumed. Ranciéite forms the iron grey to black substances in the cavern of calc-tufa. Its occurrence is probably linked with precipitation from the thermal waters together with bacterial participation. Source


Sejkora J.,Mineralogicko petrologicke oddeleni | Stevko M.,Katedra mineralogie a petrologie | Macek I.,Mineralogicko petrologicke oddeleni
Bulletin Mineralogicko-Petrologickeho Oddeleni Narodniho Muzea v Praze | Year: 2013

The minerals of the tetrahedrite isotypic series are the main ore phases at the Piesky deposit and in the past they were the most important source of copper and silver at the whole Špania Dolina ore district (central Slovakia, Slovak Republic). They occur as veinlets, impregnations or massive aggregates up to 10 cm in size, which are associated together with chalcopyrite in quartz-carbonate veins or in mineralized rocks and are often altered to the yellowish-green aggregates of amorphous Cu-Sb-Fe phases or diverse supergene minerals. The chemical composition of minerals of the tetrahedrite isotypic series from the various parts of the Piesky deposit is rather uniform. In the trigonal site Cu is dominant element and only low content of Ag (up to 0.04 apfu) was detected. The overall content of divalent metals like Fe, Zn as well as slight amount of Pb in the tetrahedral site is up to 1.3 - 1.7 apfu, which together with elevated content of Cu (higher than theoretical value of 10 apfu) suggest the presence of at least some Cu2+ in this possition. In the X possition Sb is the prevalent element, so As-rich tetrahedrite is the absolutely dominant species at the Piesky deposit. Only in one case, Sb-rich tennantite as an irregular zones up to 50 μm in size was observed in the As-rich tetrahedrite. Characteristic feature of tetrahedrite-tennantite minerals from the Piesky deposit is regular content of Bi (up to 0.14 apfu). Source


Stevko M.,Katedra mineralogie a petrologie | Sejkora J.,Mineralogicko petrologicke oddeleni | Plasil J.,Fyzikalni Ustav
Bulletin Mineralogicko-Petrologickeho Oddeleni Narodniho Muzea v Praze | Year: 2012

An interesting association of supergene uranium minerals represented by natrozippeite, zinczippeite, andersonite and zellerite was found at the 12th level of Banská Štiavnica base metal deposit. The most abundant supergene phase, natrozippeite forms bright yellow crystalline coatings which consist of tiny tabular crystals up to 5 μm in size on quartzsulfide gangue with disseminated uraninite. It is associated together with zinczippeite, gypsum and melanterite. Its refined unit-cell parameters are: a = 17.664(3) Å, b = 14.650(1) Å, c = 17.711(2) Å, β = 104.45(1)°, V = 4438(1) Å3. Electron microprobe analyses of natrozippeite yielded its average chemical composition Na2O 3.05, K2O 0.25, CaO 0.03, MgO 0.13, PbO 0.31, CuO 0.15, MnO 0.06, ZnO 0.27, Al2O3 0.12, SiO2 0.36, SO3 10.12, UO3 76.90, H2Ocalc. 8.05, total 99.80 wt. % corresponding to the empirical formula (Na2.97K0.16Mg0.10Zn0.10Al0.07Cu0.06Pb0.04Mn0.03Ca0.02)Σ3.54[(UO2)8.12(SO4)3.82(SiO4)0.18O5(OH)3]·12H2O on the basis (S+Si) = 4 apfu. Zinczippeite was found as orange-yellow fine crystalline irregular aggregates formed by tiny and imperfect thin-tabular crystals up to 10 μm in size together with natrozippeite, gypsum and melanterite on quartz-sulfide gangue with disseminated uranium mineralization. The refined unit-cell parameters of zinczippeite are: a = 8.655(4) Å, b = 14.261(4) Å, c = 17.691(8) Å, β = 104.16(4)°, V = 2117(1) Å3 and its average chemical composition is Na2O 0.26, K2O 0.48, CaO 0.23, FeO 1.12, MgO 0.50, PbO 0.60, CuO 0.27, MnO 0.25, ZnO 4.33, Al2O3 0.14, SiO2 0.42, P2O5 0.17, SO3 9.71, UO3 73.83, H2Ocalc. 8.24, total 100.53 wt. % corresponding to the empirical formula (Zn0.41Fe0.12Mg0.09K0.08Na0.06Ca0.03Cu0.03Mn0.03Al0.02Pb0.02)Σ0.89[(UO2)1.97(SO4)0.93(SiO4)0.05(PO4)0.02O2]·3.5H2O on the basis (S+Si+P) = 1 apfu. Andersonite forms rare transparent apple-green irregular crystals up to 1 mm on quartzsulfide gangue with disseminated uraninite and abundant coarse-grained aggregates of carbonate (calcite). Its refined unit-cell parameters are: a = 17.9184(6) Å, b = 23.752(1) Å, V = 6604.4(4) Å3. Qualitative chemical analysis showed only presence of Ca, Na, U, C and O which is consistent with ideal chemical composition of this mineral. Zellerite is the rarest phase in the studied mineral association, it occurs as pale-yellow spherical or reniform aggregates up to 0.2 mm on quartz-sulfide gangue with disseminated uraninite and abundant coarse-grained aggregates of calcite. The refined unit-cell parameters of zellerite are: a = 11.268(9) Å, b = 19.11(1) Å, c = 4.900(3) Å, V = 1055.2(9) Å3 and its qualitative chemical analysis showed presence of Ca, U, C and O which agrees with the ideal chemical composition of this phase. Described association of supergene uranium minerals represents sub-recent alteration products of primary uraninite, coffinite and base metal sulfides in the environment of the abandoned mine adit. Source


Uher P.,Katedra mineralogie a petrologie | Ferenc S.,Katedra Geografie | Spisiak J.,Katedra Geografie
Bulletin Mineralogicko-Petrologickeho Oddeleni Narodniho Muzea v Praze | Year: 2013

Unique chromian-nickeloan muscovite occurs in magnesite-dolomite-quartz listvenite rock (carbonatized and silicified serpentinite) from Muránska Zdychava near Revúca (Veporic Superunit, Slovenské rudohorie Mts., central Slovakia). Muscovite forms anhedral aggregates and veinlets in quartz and carbonate groundmass, up to 20 μm across. It shows emerald-green colour, electron-microprobe analyses revealed 9.5 to 12 wt. % Cr2O3 (0.52 - 0.67 apfu) and 2.1 to 4.5 wt. % NiO (0.11 - 0.25 apfu). The average crystallochemical formula of the Cr,Ni-rich muscovite is close to K0.65(Al1.13Cr0.59Ni0.19Mg0.16Fe0.05)Σ2.12(Si3.33A l0.67)Σ4.00(OH)1.90F0.10. The Ni contents belong to the highest concentrations of this element ever obtained on a mineral of mica group. The Cr-Ni muscovite is associated with accessory chromite, pyrite, and Ni-sulphide minerals (pentlandite, violarite, ullmannite and millerite). The Cr,Ni-rich muscovite and associated minerals of listvenite originated by hydrothermal-metasomatic overprint on primary, Lower Paleozoic metaultrabasic rocks during Alpine (Cretaceous) orogenesis. Source


Majzlan J.,Friedrich - Schiller University of Jena | Stevko M.,Katedra mineralogie a petrologie | Chovan M.,Institute geologickeho inzenyrstvi
Bulletin Mineralogicko-Petrologickeho Oddeleni Narodniho Muzea v Praze | Year: 2015

In this contribution, we studied mineralogy of a small, long abandoned ore occurrence near the village of Hiadeľ in the Nízke Tatry Mts. (Slovakia). An earlier mineral association consists of pyrite I, arsenopyrite, rutile, apatite, monazite, and possibly zircon. This association is located in alteration zones with abundant sheet silicates. Carbonates are found in this association but also in the milky quartz that contains no sheet silicates. The composition of the carbonates is variable; they belong to the siderite-magnesite and dolomite-ankerite solid solution, rarely to calcite. Later ore minerals are represented by stibnite, Pb-Sb sulfosalts (zinkenite, jamesonite, or robinsonite), tetrahedrite, chalcostibite, bournonite, and pyrite II. The temporal relationship among these minerals cannot be determined from our samples. Tetrahedrite is Zn-rich and Ag-poor. From a mineralogical point of view, this occurrence does not deviate from other ore deposits and occurrences known in the Tatric part of the Nízke Tatry Mts. © 2015, National Museum Prague. All rights reserved. Source

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