Journal of GEOsciences Table of Contents for the Journal of GEOsciences. List of articles from the latest print issue.http://www.jgeosci.orgen-US Journal of GEOsciences <![CDATA[ Newly described uranium mineralization with ruthefordine from former arsenic mine Giftkies, Jáchymov ore district, Czech Republic ]]> Roll M, Goliáš V, Zachariáš J, Plášil J, Falteisek L; Vol. 69, issue 2, pages 77 - 86
The Giftkies mine is the only known locality of rutherfordine within the Jáchymov ore district s. l., which is famous for the occurrence of many uranyl carbonates. Uranyl monocarbonate rutherfordine, UO2(CO3), investigated in this study, has been found in significant amounts in the abandoned arsenic mine at Giftkies site (Jáchymov, Czech Republic), together with other uranyl carbonates, common liebigite and scarce agricolaite. The possible specific conditions of rutherfordine formation prompted the detailed study with the following analytical methods. XRD methods helped identify above mentioned minerals as well as other secondary minerals reported from this site, 31 minerals in total. The mineralization sequence was investigated and determined by both optical and scanning electron microscopy to be: quartz → early siderite → late siderite → pyrite → iron oxyhydroxides → rutherfordine. This microscale investigation of textural features and element admixtures helped to create above mentioned paragenetic scheme. Further on alpha spectrometry and radiometric dating of rutherfordine helped to build a timeframe. A daughter deficiency method using 230Th/234U isotopic pair provides late Holocene ages and suggests at least two rutherfordine formation episodes (4600-2600 years BP and 1350-300 years BP respectively). According to data, we claim that supergene processes that lead to rutherfordine crystallization at the site started at the beginning of the Subboreal period and lasted until nowadays. ]]>
<![CDATA[ Manganrockbridgeite from the Jocão claim, Conselheiro Pena, Minas Gerais, Brazil: chemistry, spectroscopic and structural data ]]> Tvrdý J, Vritiška L, Filip J, Dolníček Z, Škoda R, Petr M, Malíková R; Vol. 69, issue 2, pages 87 - 98
The world’s second occurrence of the recently described manganrockbridgeite was found in a mineral assemblage in the Jocão (Cigana) pegmatite, Conselheiro Pena district, Minas Gerais (Brazil). Manganrockbridgeite forms green botryoidal-crystalline crusts with a velvety surface covering the walls of leached cavities in triphylite replaced by correianevesite and Mn-rich vivianite. The outer zone is significantly richer in Mn than the inner zone where the manganrockbridgeite passes to frondelite. Other associated minerals are hureaulite and kenngottite-like phosphate. Empirical formulae based on EPMA, Mössbauer and XPS spectroscopy are (Mn1.36Fe2+0.46Fe3+0.09Ca0.03Mg0.01  0.05)Σ2.00 Fe3+2.95(PO4)3.00(OH)3.84(H2O)1.16 for the outer zone and (Mn1.03Fe2+0.49Fe3+0.29Ca0.03Mg0.02  0.14)Σ2.00 Fe3+2.94(PO4)3.00(OH)3.81(H2O)1.19 for the inner zone of aggregates. Raman spectra and assignment of individual decomposed bands to vibrational modes show a good agreement with data published for frondelite from the Jocão locality. By powder diffraction data the studied manganrockbridgeite corresponds to the type material from Hagendorf-Süd, Germany. Unit-cell parameters for space group P21/m are a = 5.195(2) Å, b = 16.936(4) Å, c = 7.452(2) Å, β = 110.25(3)° and V = 615.1(4) Å3. ]]>
<![CDATA[ The role of jarosite group minerals in the attenuation of metals and arsenic in mine drainage system (example from the Pekelská Adit, Czech Republic) ]]> Hršelová P, Sracek O, Filip J, Hrazdil V, Malý K; Vol. 69, issue 2, pages 99 - 111
Mineralogy of stream sediments and acid mine drainage water chemistry were investigated in the Pekelská Adit in Czech Republic. Bulk solid phase composition was determined using total decomposition, X-ray powder diffraction, electron microprobe, X-ray photoelectron spectroscopy, and Mössbauer spectroscopy. Water chemistry at the principal branch is acid (pH<3.0) with high concentration of dissolved iron and sulfate, but it is close to neutral in the second stream branch and becomes more acidic only after the confluence of both branches. Minerals of alunite group including K-jarosite, plumbojarosite, and hydronium jarosite were identified in the stream sediments of acid branch by combination of complementary instrumental methods. In the acid branch, sediments comprise high contents of As (up to 8,021 ppm) and Pb (up to 4,131 ppm), but contents of Zn are much lower. In contrast, in the neutral branch, there is high content of Zn in sediments (up to 11,667 ppm) linked to goethite, but contents of As and Pb are several orders of magnitude lower. Results confirm that minerals of alunite group can be very efficient in trapping of dissolved contaminants and play crucial role in the natural attenuation of dissolved metals and metalloids in mine drainage waters. ]]> Original paper
<![CDATA[ Origin of apatite-dominated rock penetrating the volcaniclastic fill of the Pleistocene Bažina maar (western Czech Republic) ]]> Rapprich V, Vylita T, Molnár K, Hora JM, Benkó Z, Čurda M, Magna T, Koubová M, Pour O, Hrubcová P, Fischer TJ; Vol. 69, issue 2, pages 113 - 127
The sequence of alkaline basaltic lavas and associated pyroclastic deposits that fill Bažina maar in western Bohemia is transected by a vein of apatite-dominated rock revealed in the S4 borehole. Aside from solid vein fill, apatite also impregnates a significant part of the drilled volcanic sequence. In the main body (depth 60.00-66.60 m), apatite occurs in two texturally distinct types: common cauliflower-type apatite (type 1) is transected by veinlets of coarser (0.2 mm long) apatite crystals (type 2). Both types have grown into open spaces suggesting precipitation from fluids rather than crystallization from melt, which is consistent with generally low trace element contents with slight enrichment in Cs, Sr, U and Pb. Relative to other local Plio-Pleistocene volcanic rocks, apatite vein-fill is shifted in 87Sr/86Sr towards more radiogenic values (0.7053-0.7054). This suggests that fluids carrying mantle-derived ions mixed with groundwater interacting with granitic country-rock, as also evidenced by the purely crustal character of noble gases trapped in apatite. Unlike the mofettes occurring along the Mariánské Lázně Fault on the eastern margin of the Cheb Basin, the 4He/3He ratios from Bažina apatite do not indicate mantle noble gas contribution. According to our model, the originally Sr-P-rich fluids with low 87Sr/86Sr mixed with Cs-U-enriched groundwater circulating in country-rock granites with radiogenic 87Sr/86Sr. Therefore, present-day CO2 outgassing through mofettes related mainly to the Mariánské Lázně Fault (eastern margin of the Cheb Basin) is likely independent of, and unrelated to, volcanism of the Cheb-Domažlice Graben. ]]>