New data on mineralogy of the Vysoký Kámen deposits near Krásno, Slavkovský les area, Czech Republic (original) (raw)
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Mineralogy of the stibnite deposit at Chříč near Rakovník (Czech Republic)
2019
A small abandoned Sb-deposit at Chříč near Rakovník (Central Bohemia, Czech Republic) is represented by hydrothermal veins hosted by metagreywackes and metasiltstones of the Barrandian Neoproterozoic, which were contactly metamorphosed by dyke intrusion of a Paleozoic lamprophyre (spessartite). A rich sulphidic association containing together with stibnite, pyrite and arsenopyrite also nineteen subordinate or accessory ore minerals (sphalerite, berthierite, galena, tetrahedrite, freibergite, chalcopyrite, ullmannite, jamesonite, boulangerite, cobaltite, costibite, gersdorffite, bournonite, greenockite, native silver and native antimony) was found during our study of dump and museum material. Very interesting is especially the presence of Agand Se-rich minerals including Ag-rich tetrahedrite, freibergite, naumannite, clausthalite and Se-rich stephanite. The gangue is formed mainly by quartz, but in a lesser amount there occur also either older and younger carbonates (dolomite-ankerit...
Comparative analysis of telluride occurrences found in the territory of Slovakia and Transcarpathians (Ukraine) has shown that there is distinct difference between the mode of Au;Ag;Bi;Te;Se mineralization of these regions. But within the area of distribution of neovolcanites Bi;Te;Se;S mineralization is generally represented by similar mineralogical phases. In the Transcarpathian region bismuth tellurides (tsumoite, pilsenite, joseites, native bismuth and poorly studied sulpho;seleno; tellurides of bismuth) were found only in metasomatites as secondary quartzites of the Vyghorlat;Guta ridge area. (Il'kivtsy, Podulky, Smerekiv Kamin'). The similar mineralization have been also found in some neovolcanites of Slovakia (Poruba pod Vigorlatom, Remetska Hamra).
Journal of Petrology, 1997
have the OH-F sites fully occupied by fluorine. Also, accessory The Podlesı´granite stock in the western Krušné Hory (Erzgebirge) phosphates were formed during late magmatic crystallization of the Mountains, Czech Republic, represents an extremely fractionated, strongly P, F-enriched residual melt. Thus, the mineralogical data strongly peraluminous, F-and P-rich, rare-metal granite system of reflect the presence of two crystallization events within the dyke Late Variscan age. The stock, studied in drill core of 300 m length, granite and pegmatite. The presence of two melts, parental and is formed by albite-protolithionite-topaz granite ('stock granite', residual, the latter strongly enriched in phosphorus, has been also depth 50-300 m) and shows geochemical and textural zoning. The confirmed by study of melt inclusions in quartz from samples of stock granite is rich in P (~0·5 wt %), F (0·5-1·2 wt %), Rb the stock granite in its dyke-bearing uppermost part. Mineral, melt (~1000 ppm), Li (500-1000 ppm) and Cs (100-150 ppm), inclusion and whole-rock chemical data from all rock types provide and poor in Ti, Mg, Fe, Ca, Sr, Ba, Zr and rare earth elements evidence for two stages of granite evolution, namely crystallization (REE). Within the uppermost part of the stock (depth 57-115 m), from
Canadian Mineralogist, 2016
Slawsonite is an extremely scarce natural member of the Feldspar Group, occurring in less than 10 known localities worldwide. We report three new slawsonite occurrences (inČert'ák, Krmelín, andŘepiště) in rocks of the Cretaceous teschenite association in the Czech Republic. AtČert'ák, a tabular sill of ''teschenite'' (in fact analcime syenite, based on its mineral composition) is one of the most alkaline examples of the teschenite association rocks. It shows differentiation to a coarsergrained core enriched in amphiboles, with diffuse transition to the outer zones. Rare thin leucocratic ''aplite'' dikes contain slawsonite, celsian, microcline, natrolite, prehnite, analcime, and thomsonite-Ca. Slawsonite forms aggregates exhibiting symplectite-like microstructures up to 2 mm long and is associated with euhedral zoned celsian micrograins up to 100 lm in size. Wavelength dispersive X-ray analyses indicate that the chemical composition of slawsonite ranges from Sl 90.4 Cn 3.4 An 1.7 Ab 3.1 Or 1.4 to Sl 60.3 Cn 8.7 An 6.9 Ab 18.3 Or 5.8 ; the composition of celsian ranges from Cn 95.8 An 0.4 Ab 1.0 Or 2.3 Sl 0.5 to Cn 70.1 An 0.5 Ab 2.2 Or 6.3 Sl 20.9 ; and the Na-rich microcline exhibits a composition of Or 58.3 An 2.8 Ab 29.4 Cn 6.4 Sl 3.1. Slawsonite from Krmelín andŘepiště occurs in a similar geological setting, as aggregates up to 0.3 mm in size that are confined to leucocratic dikes at the endo-contacts of teschenite sills or lava pods. We suggest that slawsonite forms pseudomorphs after nepheline or possibly after plagioclase. Whole-rock geochemistry shows that local teschenites have an affinity for alkali basaltoid rocks typical of MORBs, but are significantly enriched in incompatible elements such as Rb, Ba, Th, U, Ta, Nb, and Sr. With regard to the obvious presence of autometamorphic hydrothermal alteration, we propose that bodies of teschenite association rocks should not be described as dikes; instead, a model of lava pods should be applied.
The Canadian Mineralogist, 2009
Newly discovered assemblages of numerous ore minerals disseminated in schists, amphibolites and mylonites at their contacts with a dolomite lens exploited at Rędziny, in the northeastern Bohemian Massif, Western Sudetes, Poland, was used in an evaluation of the thermochemical conditions under which specific, and in some cases rare, phases formed. Arsenopyrite, cassiterite and associated base-metal sulfides crystallized at temperatures lower than 550°C. The Ag-bearing sulfosalts pavonite, benjaminite, makovickyite, gustavite, berryite, matildite, giessenite, izoklakeite, cosalite, freibergite and tetrahedrite crystallized along with Ag-bearing galena in the temperature range ca. 350-280°C. They preceded the Cu-Pb-Bi(Sb) sulfosalts wittichenite, bournonite, aikinite-group minerals, emplectite and Ag-poor tennantite, which crystallized from about 300°C to even below 200°C. Kësterite and černýite crystallized at temperatures about 350°C, černýite occurring only in Zn-depleted environments. Ferrokësterite and petrukite, occurring with Zn-enriched chalcopyrite as inclusions within (Fe,Cd,Cu,Sn)-enriched sphalerite, are products of decomposition at 340-270°C of a higher-temperature (Zn,Cd,Cu,Fe,Sn) sulfide. Chatkalite formed as a metastable phase at the SnO 2-SnS equilibrium at temperatures of about 270-260°C; stannoidite crystallized from 270°C to 250-240°C, at which point mawsonite began to crystallize. Unknown Sn-bearing sulfides, with compositions varying between Cu 4 Fe 3 SnS 8 and Cu 10 SnS 8 , crystallized at probably still lower temperatures. Bismuth sulfides (bismuthinite and an unknown Pb-Bi-S phase), sulfoselenides (ikunolite) and sulfotellurides (tetradymite, joséite-A, joséite-B and an unknown BiTe -S phase) crystallized under varying conditions: tetradymite at about 300°C, ikunolite at 270-240°C, bismuthinite from about 300 to 220°C, and joséite-A and joséite-B clearly below 240°C.
Mineralogy and Petrology, 2018
The Au-Ag-Pb-Zn-Cu epithermal deposit Banská Hodruša of intermediate-sulphidation type is located in the Middle Miocene Štiavnica stratovolcano on the inner side of the Carpathian arc in Slovakia. This deposit represents an unusual subhorizontal multi-stage vein system, related to processes of underground cauldron subsidence and exhumation of a subvolcanic granodiorite pluton. Veins are developed on a low-angle normal shear zone, possibly representing a detachment zone in andesitic wall rocks that formed during emplacement and exhumation of the granodiorite pluton. The deposit consists of two parts, separated by a thick sill of quartz-diorite porphyry. The eastern part is currently mined, and the western part has already been depleted. The Banská Hodruša mineralization was formed during four stages: (1) low-grade silicified breccia at subhorizontal structures at the base of the deposit; (2) stockwork of steep veins with rhodonite-rhodochrosite, quartz-sulphide-carbonate and quartzgold assemblages; (3) thin quartz-gold veins with medium dip in tension cracks inside the shear zone and complementary detachment hosted quartz-base metals-gold veins; (4) Post-ore veins. Gold and electrum (920-730) occur as intergrowths with base metal sulphides or hosted in quartz and carbonates, accompanied by Au-Ag tellurides (hessite, petzite). Rare Tepolybasite and Cu-cervelleite result from re-equilibration of early Te-bearing minerals during cooling. Sulphide minerals include low Fe sphalerite (~ 1.25 wt%), galena, chalcopyrite, and pyrite. The wall rock alteration is represented mostly by adularia, illite, chlorite, quartz, calcite and pyrite. Precipitation of gold, Au-Ag tellurides, Mn-bearing minerals and adularia resulted from boiling of fluids due to hydraulic fracturing, as well as opening of dilatational structures within the shear zone.
Journal of the Czech Geological Society
Electron microprobe analyses were made on micas, amphiboles, feldspars, chlorites and accessory minerals in lamprophyric dykes (kersantites, minettes, spessartites), and in associated mafic diorite to tonalite porphyries (porphyrites) of the Kruné hory (Erzgebirge) area and Mariánské Láznì region in Western Bohemia (Czech Republic). All studied rocks are altered to various degrees during deuteric and/or postmagmatic stages of evolution. The only primary mafic mineral preserved in all rock types is Mg-biotite to phlogopite, in spessartites and some diorite porphyries also Ti-rich hornblende corresponding to titanian magnesiohastingsite to kaersutite. Magmatic biotites are relatively rich in Ti with limited variations in their Mg/Fe ratios, evidently re-equilibrated during cooling or re-heating. Olivine is totally replaced by pilitic pseudomorphs and by biotite-actinolite clots. Phenocrystic clinopyroxene is completely uralitized, often in well-preserved original shapes. The secondary amphiboles correspond to Si-rich magnesiohornblende to actinolite. Chlorite and epidote are rather scarce and their important occurrences are restricted to limited number of samples. Instead of chloritization typical of lamprophyres in other parts of the Bohemian Massif, most samples are affected by secondary biotitization. Effects of greisenization sensu stricto were observed in some lamprophyres from Krupka where Li-bearing dark micas rich in Si and Mg originated.
Journal of Geosciences, 2008
Metabasic rocks form an important constituent of the Chýnov and Český Krumlov units belonging to the Varied Group (Moldanubian Zone, south Bohemia). The amphibolites are dominated by amphibolite-facies mineral assemblages of mainly tschermakitic amphibole and plagioclase. Hornblendes show compositional variation with Si ~ 6.5 apfu, Mg/(Mg + Fe) ~ 0.5 and (Na + K) A ~ 0.5 apfu. Garnet with clinopyroxene are subordinate and occur in a few samples only. No relics of previous greenschist-or granulite-facies assemblages have been observed, most likely due to the relatively simple metamorphic history. The petrology indicates rather close correlation of the Chýnov and Český Krumlov units. The similarities include presence of dolomite in carbonate bodies, graphite schists, rocks with marialitic scapolite, locally also Ti-andradite (± magnetite, epidote) oxidic assemblages and thin layers of Mn-rich garnet-quartz rocks. However, there is a major difference in the oxidation state. Most Chýnov amphibolites have Fe 2 O 3 /FeO = 0.70-1.00 and their protolith probably experienced an early incipient oxidation. Great deal of the parental basalts thus could have been effusive. The Český Krumlov amphibolites have Fe 2 O 3 /FeO ≤ 0.4, perhaps because they show much closer association with graphite schists that could have been responsible for the reduction of the adjacent rock units. The dataset is dominated by EMORB-like tholeiite basalts interpreted as having been derived by Early Palaeozoic melting of a strongly depleted mantle source (ε 50 Nd 0 = +8.6 to +9.4; T D Nd M = 0.43-0.50 Ga). This argues stoutly against Precambrian age of the Varied Group in south Bohemia. The composition of the remaining samples reflects contamination by upper continental crust (ε 50
Grumiplucite from the Rudňany deposit, Slovakia: a second world-occurrence and new data
Journal of Geosciences, 2015
Grumiplucite, ideally HgBi 2 S 4 was identified at the Droždiak vein, Rudňany deposit (Spišsko-gemerské Rudohorie Mts., Slovakia). This rare Hg-sulfosalt forms metallic lead-grey to steel-grey, prismatic to acicular crystals up to 1 cm long, often grouped into irregular aggregates. It occurs in cavities of siderite with abundant cinnabar, Hg-rich tetrahedrite and chalcopyrite aggregates. Minor quartz or barite crystals and microscopic aggregates of Sb-rich bismuthinite to Birich antimonite were also observed. On the basis of chemical analyses, two types of grumiplucite were distinguished at the Rudňany deposit. The first is close to an ideal composition and has empirical formula Hg 0.99 Bi 1.94 S 4.08 (based on 7 apfu). The second is characterized by regularly elevated contents of Sb ranging from 0.02 to 0.77 apfu. Grumiplucite is monoclinic, space group C2/m, with unit-cell parameters refined from X-ray powder data: a = 14.172(2), b = 4.0525(7), c = 13.975(1) Å, β = 118.257(8) o and V = 707.0(2) Å 3 (Sb-free) and a = 14.183(1), b = 4.0538(5), c = 13.980(1) Å, β = 118.239(1) o and V = 708.1(2) Å 3 (Sb-rich). Raman spectra for grumiplucite crystals with variable Sb contents are mutually well comparable. Therefore it seems that different Sb occupation does not affect the energy and intensity of Raman bands and they significantly differ from spectra of particularly structure-related mineral livingstonite, HgSb 4 S 8. The dominant feature in the Raman spectra of grumiplucite is a series of spectral bands that corresponds to the stretching and bending vibrations of BiS 5 polyhedra and Hg-S bonds.