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Horní Počernice, Czech Republic

In this research 18 samples of tetrahedrite containing mercury were collected from six localities in the Czech Republic, Slovakia and Bosnia. The samples were subjected to detail microprobe and x-ray diffraction analyses and subsequent refinement of unit-cell parameters. Tetrahedrites from the Jedová Hora locality (Czech Republic) are rich in mercury (1.46-1.73 apfu); tetrahedrites from the Rudňany deposit (Slovakia) have a variable content of Hg, Fe and Zn (Hg rich samples with 1.47-1.79 apfu of Hg; Fe rich sample with 1.06 apfu of Fe and Zn rich sample with 1.79 apfu of Zn); tetrahedrites for the Rožňava deposit (Slovakia) are mostly Fe rich (1.53 - 1.75 apfu); Hg rich sample from Rožňava contains 1.65 apfu of Hg. Two samples of tetrahedrites from the Nižná Slaná deposit (Slovakia) are rich in Hg (1.07 and 1.39 apfu); analyzed sample from the Slovinky deposit (Slovakia) is rich in Zn (1.13 apfu). Samples from the Maškara deposit (Bosnia) contain more Fe than Hg (Fe: 0.93 - 1.33 apfu; Hg: 0.19-0.76 apfu). The mercury content in the samples showed a positive linear correlation to the unit cell parameters (0.19 apfu ~ 10.32 Å to 1.79 apfu ~ 10.46 Å). © 2014, Bull. mineral.-petrolog. Odd. Nár. Muz. (Praha). All rights reserved.

Pazout R.,Vysoka skola chemicko technologicka Prague | Jiri Sejkora A.,Mineralogicko petrologicke oddeleni
Bulletin Mineralogicko-Petrologickeho Oddeleni Narodniho Muzea v Praze | Year: 2015

A rare oxychloride of lead and antimony, the mineral nadorite, was found in an ore sample from the Kutná Hora ore district, Central Bohemia. It is the first occurrence of this mineral in Czech Republic. The mineral was identified in a polished section as a dark elongated grain approximately 30 μm accros, enclosed in boulangerite in association with galena. The chemical composition of nadorite is close to the ideal formula of this mineral with only minor contents of As (0.02 - 0.04 apfu) which probably substituted Sb. The average chemical composition (mean of 3 point analyses) of nadorite: Pb 51.88, Sb 31.45, As 0.61, Ocalc. 8.31, Cl 9.25, total 101.51 wt. %, corresponds to the empirical formula Pb0.97(Sb1.00As0.03)Σ1.03O2.00Cl1.01 on the basis of Pb+Sb+As+Cl = 3 apfu. © 2015, National Museum Prague. All rights reserved.

Stevko M.,Comenius University | Gramblicka R.,Severoceske doly a.s. | Malikova R.,Mineralogicko petrologicke oddeleni
Bulletin Mineralogicko-Petrologickeho Oddeleni Narodniho Muzea v Praze | Year: 2015

An interesting association of supergene minerals represented by anglesite, aragonite, brianyoungite, cerussite, gypsum, hemimorphite, malachite, mimetite, pyromorphite and wulfenite was found at the Čavoj base metal deposit, Strážovské vrchy Mts., Slovak Republic. Brianyoungite occurs as white crystalline coatings and irregular to spherical aggregates, which consist of thin-tabular crystals up to 0.1 mm in size. It was found together with aragonite and gypsum on the surface of ore fragments at the dumps of Geschenk and Ferdinand shaft. The refined unit-cell parameters of brianyoungite from the powder X-ray data are: a 15.710(8) Å, b 6.273(7) Å, c 5.45(1) Å, V = 537(1) Å3. Cerussite is the most abundant supergene phase. It forms well developed colourless to white tabular or prismatic crystals up to 5 mm in size, associated together with anglesite, mimetite, pyromorphite and wulfenite. Its refined unit-cell parameters are: a 5.189(1) Å, b 8.507(2) Å, c 6.152(1) Å, V 271.56(9) Å3. Hemimorphite was identified at the dumps situated near Strieborná adit as white hemispherical crystalline aggregates up to 2 mm in the fissures of sphalerite-rich gangue. It is orthorhombic, space group Imm2 and the unit-cell parameters refined from X-ray powder diffraction data are: a 8.3634(8) Å, b 10.711(1) Å, c 5.1134(5) Å, and V 458.07(8) Å3. Mimetite is rare mineral and it occurs only at the Baniská area. It forms bright yellow to yellowish-green crystalline aggregates and crusts, which are composed by prismatic crystals up to 1 mm in size. Its unit-cell parameters refined from powder X-ray data are: a 10.236(10) Å, c 7.4126(9) Å and V 673(1) Å3. Mimetite from the Čavoj deposit contain only minor amounts of Ca (up to 0.33 apfu) and P (up to 0.39 apfu) with the empirical formula (average of 6 point analyses) corresponding to (Pb5.11Ca0.21)Σ5.32[(AsO4)2.77(PO4)0.23]Σ3.00Cl1.17 on the basis of P+As+V+Si+S=3 apfu. Pyromorphite was identified in several samples from the Ferdinand shaft dump as pale-green to pale-yellow prismatic crystals up to 2 mm in size, which are often grouped to the crystalline crusts and aggregates together with cerussite and wulfenite. The refined unit-cell parameters of pyromorphite are: a 9.986(8) Å, c 7.3528(3) Å and V 635.0(5) Å3. Only minor amounts of Ca (up to 0.19 apfu) and As (0.07 apfu) were detected in studied samples of pyromorphite and its empirical formula (average of 9 point analyses) is corresponding to (Pb4.97Ca0.10)Σ5.07[(PO4)2.95 (AsO4)0.05]Σ3.00Cl1.15 on the basis of P+As+V+Si+S=3 apfu. Wulfenite is rare supergene phase at the studied locality (dump of Ferdinand shaft) and it occurs as well developed, orange pyramidal crystals up to 1 mm in size together with cerussite and pyromorphite. It is tetragonal, space group I41/a and its unit-cell parameters refined from X-ray powder diffraction data are: a 5.435(1) Å, c 12.1065(2) Å and V 357.59(9) Å3. Its chemical composition is close to the end member formula with only insignificant amounts of P and As (both up to 0.01 apfu) and empirical formula (average of 5 point analyses) corresponding to Pb1.00[(MoO4)0.98(AsO4)0.01(PO4)0.01]Σ1.00 on the basis of Mo+W+As+P=1 apfu. On the basis of detailed paragenetic study two principal associations of supergene minerals were distinguished at the Čavoj deposit: a) supergene phases (e.g. cerussite, hemimorphite, mimetite, pyromorphite or wulfenite) formed by in-situ decomposition of primary ore minerals in the supergene zone or b) supergene minerals of sub-recent origin, which were formed by the weathering of ore fragments in dump environment (e.g. aragonite, brianyoungite and gypsum). © 2015, National Museum Prague. All rights reserved.

Sejkora J.,Mineralogicko petrologicke oddeleni | Skacha P.,Mineralogicko petrologicke oddeleni
Bulletin Mineralogicko-Petrologickeho Oddeleni Narodniho Muzea v Praze | Year: 2015

Mineral phases of clausthalite - galena solid solution were found at samples of siderite - fluorite - quartz gangue from the abandoned fluorite - baryte mine Běstvina, Železné hory Mountains (eastern Bohemia, Czech Republic). They occur as irregular grains up to 0.5 mm in size and tiny veins in coffinite and rarely uraninite. The solid solution series covers the range PbSe1.00to Pb(S0.58Se0.42) virtually free of gaps and two groups of Se-containing galena with 0.10 - 0.13 and 0.26 - 0.27 apfu Se, respectively. Younger sulphides (pyrite, sphalerite, chalcopyrite) were found in the association. Pyrite is As-rich with empirical formula Fe1.00(S1.98As0.02)Σ2.00. Sphalerite with minor contents Fe, Cd and Cu has empirical formula (Zn0.98Fe0.01Cd0.01)Σ1.00S1.00. Chemical composition of chalcopyrite is possible to express as Cu0.98(Fe0.98Zn0.02)Σ1.00S2.02. © 2015, National Museum Prague. All rights reserved.

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).

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