The rare Hg-sulfosalt, marrucciite, with ideal formula Hg 3 Pb 16 Sb 18 S 46 , was found in the Gelnica ore deposit (Spišsko-Gemerské Rudohorie Mts., Slovak Republic). It occurs as acicular crystals up to 0.5 mm in length and fine-grained aggregates up to 1 mm in quartz (+siderite/dolomite) gangue in association with other sulfosalts (zinkenite, scainiite, boulangerite, chalcostibite, bournonite) and cinnabar. It is opaque, dark steel grey to greyish black, sometimes tarnished to a bronze-brown tint, has a dark grey streak with a very weak reddish tint and a metallic luster. Marrucciite is very brittle but thin acicular crystals are flexible. One good cleavage parallel to the elongation of the crystals was observed. The VHN 20g microhardness is 85 (69-101) kp/mm 2 and corresponds to a Moh's hardness of c. 2; the calculated density is 6.00 g.cm . In reflected light, marrucciite is white to greyish white with a weak yellowish tint, distinct bireflectance and white-white grey pleochroism. Under crossed polars, it has distinct anisotropy, with rotation tints in shades of grayish brown and dark brown. Dark red internal reflections were observed only rarely. Marrucciite is monoclinic, space group C2/m with a 48.12 (1)
A mineral association with dominant pyrrhotite, tsumoite and gold, accompanied by minor tetradymite and pilsenite, has been found in material from the main vein of the abandoned Au deposit Libčice near Nový Knín, 25 km SSW of Prague, central Bohemia, Czech Republic. Tsumoite forms abundant silvery grey tabular aggregates up to 1-4 mm in size. The mineral is grey-white to very weakly beige-coloured in reflected light, anisotropic, with VHN microhardness 68 (63-76) kg/mm 2 , with K VH = 1. 14. Gold contains low Ag (up to 4 wt. %) and Hg (up to 1 wt. %). The studied mineral association formed at elevated temperatures (>300 ºC), probably at two stages differing in bismuth activity, as well as f S2 and f Te2 values. Alternatively, the two stages could have reflected variation of hydrothermal and metamorphic process in space and time.
Clinopyroxene-garnet scheelite skarn containing accessory niobian titanite, native bismuth and Bi-tellurides of the Bi 2 X and Bi 5 X 3 series, together with Fe-and Fe-As sulphides, is associated with the contact of chondrodite marble with melanocratic granite-quartz syenite (durbachite). Hedenbergite-rich vein in this marble can be considered as an additional type of skarn. The presence of accessory niobian titanite is typical, in particular, of the veins. In addition to increased Nb contents (≤ 10.6 ) with R 4+ accompanied by low contents of Na in titanite correspond to the substitutions Al(OH,F)(TiO) -1 and Al(Nb,Ta)Ti -2 . Niobian titanite has anomalous composition if compared to skarn mineral assemblages worldwide. The Bi-(sulpho-) telluride with empiric formula Bi 1.98 (Te 0.66 S 0.34 Se 0.02 ) Σ1.02 is a member of the Bi 2 X series, whose members were described from numerous localities as unnamed minerals. In contrast to the published data this phase contains increased sulphur contents up to 0.33 apfu. The second Bi-(sulpho-) telluride with empiric formula (Bi 4.51 Fe 0.40 Cd 0.03 Pb 0.02 Sb 0.01 As 0.01 ) Σ4.98 (Te 1.58 S 1.36 Se 0.08 ) Σ3.02 is probably a S-rich member of the Bi 5 X 3 series. In the evolution of the skarn it is possible to distinguish stage I responsible for the formation of the older Mg-and younger Ca-skarns, and stage II, characterised by increased Fe contents. The scheelite-sulphide mineralization was formed during a third (retrogression) stage followed by brittle deformation. Emplacement of siderite ± quartz veins represents the fourth (terminal) stage of mineralization.
Unusual high-to low-T sulphide mineralization with Ni-(Bi, Ag) phases was examined at the NYF intragranitic pegmatite No. III from Vepice near Kovářov enclosed in the Milevsko Pluton, Moldanubian Zone, Southern Bohemia. Zoned pegmatite dike, up to 30 cm thick, has transitional contact with host durbachite and its internal structure includes transitional unit, border granitic unit, graphic unit, blocky unit (Kfs+Qz), quartz core and small miarolitic pocket. Sulphide mineralization locally associated with calcite and fluorite is represented by common pyrite with minor galena, accessory chalcopyrite, sphalerite, marcasite, native Bi and Ni-(Bi, Ag) minerals -argentopentlandite, parkerite and pentlandite. It is developed in small miarolitic pockets and on pegmatite fractures cutting all pegmatite units. Irregular anhedral grains and aggregates of argentopentlandite, < 200 μm in size, associated with chalcopyrite, have empirical formula Ag 0.97 (Fe 4.88 Ni 3.10 Cu 0.04 Co 0.01 ) Σ8.03 (S 7.96 As 0.03 ) Σ7.99 . Zoned irregular aggregates of parkerite, 20-30 μm in size, are typically associated with pentlandite, or overgrow galena and yield empirical formula (Ni 3.02 Fe 0.02 Co 0.01 ) Σ3.06 (Bi 1.73 Sb 0.05 As 0.04 ) Σ1.92 S 2.02 . Pentlandite is present in two morphological forms: rare lenticular to isometric anhedral grains, ≤ ~200 μm in size, and numerous small tabular crystals, ≤ 20 μm in length, in subparallel arrangement rimming aggregates of other sulphides. Empirical formula is (Ni 4.57 Fe 4.14 Co 0.25 ) Σ8.96 (S 8.01 As 0.02 ) Σ8.03 . Evaluation of relative chronology of the sulphide minerals is complicated mainly due to complex textural relations. Pyrite + marcasite are likely pseudomorphs after pyrrhotite as the earliest phase whereas pentlandite and native Bi are among the latest. Early sulphides (pyrrhotite, chalcopyrite, sphalerite, argentopentlandite) crystallized at T < ~550-400 °C, whereas pyrite, marcasite, galena, parkerite, and native Bi at T < 240 °C. Cooling of the system below T ~200 °C appeared soon after transformation of pyrrhotite to pyrite+marcasite aggregates. Sulphides manifest that concentrations of Ni in residual pegmatite melt and exsolved fluids were high enough to facilitate saturation of Ni-sulphides. Very high Ni/Co ratio in sulphides reflects a much lower concentration of cobalt in durbachite. The examined Ni-(Bi, Ag) sulphides manifest that high concentrations of highly compatible Ni in parental granite may be reflected in accessory minerals from its pegmatite.
The Padrť Stock is a small (~5 km 2 ) intrusion located near the SE margin of the Teplá-Barrandian Unit, Bohemian Massif, several kilometers away from the NW periphery of the Central Bohemian Plutonic Complex. On outcrops, which are all located close to the contact of the stock with Neoproterozoic sedimentary rocks, two types of granitoids were detected, fine-to medium-grained hornblende-biotite Padrť granodiorite, and, along its SW margin, fine-to medium-grained partly porphyritic biotite Teslíny leucogranite. The U-Pb zircon dating of the more voluminous Padrť granodiorite by laser ablation ICP-MS yielded a magmatic age of 342.8 ± 1.1 Ma, which is slightly lower than are the published age data for the nearby Blatná suite granitoids of the Central Bohemian Plutonic Complex. The Re-Os dating of molybdenite occurring in quartz veins within a quartzite lens in close exocontact yielded ages of 337.2 ± 2.4 Ma and 339.8 ± 2.5 Ma (two samples). The data indicate that the formation of molybdenite postdated that of the magmatic rock. This is in agreement with relatively low-temperature deposition of quartz related to formation of the molybdenite, as indicated by the fluid inclusions (280 to 300 °C). characterized with respect to petrology, geochemistry and ages of individual intrusions (e.g., Janoušek et al. 1995;Holub et al. 1995Holub et al. , 1997aJanoušek et al. 2000aJanoušek et al. , 2000bJanoušek et al. , 2004Janoušek et al. , 2010Žák J et al. 2005a, b, 2009. The ages of the main-phase plutons within the CBPC range from 354 ± 4 Ma to 337 ± 1 Ma. Deeper within the TBU and another 25 km to the W, small early-Variscan Štěnovice Pluton (~27 km 2 , granodiorite-tonalite) occurs, for which zircon U-Pb dating yielded an age of 375 ± 2 Ma (Žák J et al. 2010). KeywordsThe Padrť Stock is little known due to its location inside the Brdy Military Training Area with restricted access (1927-recent) and because it is largely concealed beneath Quaternary cover. Rather controversial views regarding the petrology and extent of the Padrť Stock were presented in the geological maps and short papers (e.g., Fediuk 2008). The purpose of this study is not only to bring new petrological and geochemical insights, but also provide U-Pb age for the Padrť Stock. The research focused also on sub-economic molybdenite mineralization in quartz veins within a thermally-metamorphosed quartzite at its exocontact. Lastly, in order to improve the
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