Výskyty unikátního monometalického stříbrného zrudnění na žíle H14F3 mezi 7. a 9. patrem šachty č. 21 Háje, příbramský uran-polymetalický revír (Česká republika)

Pages

230-254

Citation

LITOCHLEB, Jiří, SLEPIČKA, Vladimír, KNÍŽEK, František, SEJKORA, Jiří, ŠKÁCHA, Pavel a JEBAVÁ, Ivana. Výskyty unikátního monometalického stříbrného zrudnění na žíle H14F3 mezi 7. a 9. patrem šachty č. 21 Háje, příbramský uran-polymetalický revír (Česká republika). Bulletin mineralogicko-petrologického oddělení Národního muzea v Praze. Prague: National Museum, 2012, 20(2), 230-254. ISSN 1211-0329 (print), 1804-6495 (online). Also available from: https://www.nm.cz/en/periodicals/bmpholnrhmvp/20-2/vyskyty-unikatniho-monometalickeho-stribrneho-zrudneni-na-zile-h14f3-mezi-7-a-9-patrem-sachty-c-21-haje-pribramsky-uran-polymetalicky-revir-ceska-republika

Bulletin mineralogicko-petrologického oddělení Národního muzea v Praze | 2012/20/2

During the preliminary exploration for the silver ore on the veins H14F and H14F3, between 6th and 9th level of the shaft No. 21 in the vein node Háje (Příbram uranium and base - metal ore district, Central Bohemia, Czech Republic), occurrences of monometallic Ag ores represented by native silver, dyscrasite, allargentum and Ag-Sb sulphides were found in years 1980 - 1990. We accumulated a detailed geological and mineralogical profile of a unique silver mineralization of the vein H14F3 between 7th and 9th level of the shaft No. 21 (mining blocks HD14F3-901, HD14F3-801, HD14F3-701) with emphasis on formerly undiscovered or insufficiently described silver and antimony minerals. Siderite and calcite represented the most abundant gangue minerals. Galena, sphalerite and löllingite are fairly rare sulphides on the locality. Allargentum was found in association with dyscrasite and it probably represents its hydrothermal alte- ration product. Its empirical formula is Ag0.85(Sb0.14As0.01)Σ0.15. Andorite forms prismatic crystals under 1 mm in association with miargyrite crystals. Nchem values vary between 4.17 - 4.63 and the percentage of andorite substitution varies between 91 - 102. Native antimony occurred rarely as irregular aggregates up to 0.3 mm closely growing together with dyscrasite on the border of miargyrite grains. Its empirical formula is Sb0.99As0.01S0.01. Stibnite was found rarely in form of typical radial aggregates or individual crystals to 15 mm. Its empirical formula is Sb2.02S2.98. Sb-rich arsenic was found as three morphological and genetically distinct generations. It is the most common ore mineral in the upper vein interval around the 7th level. The chemical composition of all 3 generations is very similar. Except for the dominating arsenic (0.91 - 0.99 apfu) significant Sb contents (0.01 - 0.09 apfu) and minor Ag and S content were also found. Dyscrasite is the most interesting ore mineral in the locality with many morphological varieties from typical columnar, through tabular to thin prismatic crystals. Dyscrasite is usually zonal, zones correspond to distinct ratios of Ag/Sb and fewer also to Sb/Hg ratios. Freibergite was found as irregular grains up to 150 μm in association with silver on the 8th level. Its empirical formula is Ag6(Cu4.28Ag0.34)Σ4.62(Fe1.79Zn0.08)Σ1.87(Sb4.23As0.07)Σ4.30S12.22. Freieslebenite occurred as very rare idiomorphic crystals to 0.2 mm growing on arsenic III in calcite. Its empirical formula is Pb0.99Ag1.03Sb1.01S2.97. Galena was found in form of grains up to several cm large in association with Sb arsenic and also as microscopic inclusions growing in silver or semseyite. Galena is chemically very pure only with small amount of Sb. Löllingite forms mostly silver bands on the sides of vein fillings consisted of individual lenticular crystals to 1 mm. Its empirical formula is (Fe0.79Ni0.20Co0.03)Σ1.02(As1.88Sb0.04 S0.07)Σ1.99. Miargyrite forms pseudomorphosis after dyscrasite and Sb arsenic or individual crystals on the 7th level. Average empirical formula of all types of miargyrite can be expressed as Ag1.03(Sb1.01As0.01)Σ1.02S1.95. Pyrargyrite was found only on specimens from the 8th level in association with native silver as grains and pseudomorphoses after dyscrasite up to 2 cm. Its empirical formula is Ag3.15(Sb0.96As0.02)Σ0.98S2.86. Pyrrhotite forms tabular bronze magnetic crystals to 2 mm. Fe content (1 apfu S) vary between 0.913 - 0.940 apfu, which for empirical formula Fe1-xS correspond to values of x = 0.06 - 0.09. Semseyite was found rarely in form of microscopic polymineral tin-white aggregates growing on arsenic II together with andorite and miargyrite crystals. Its empirical formula is (Pb8.63Ag0.26)Σ8.89(Sb8.15As0.04)Σ8.19S20.93. Sphalerite occurred mainly as orange to red crystals and grains, growing in arsenic II (7th level), or as microscopic xenomorphic aggregates growing on silver (8th level). Sphalerite usually contains constant Fe contents up to 0.01 apfu and Cd up to 0.003 apfu. Younger sphalerite generation of which strong catodoluminiscence is typical has Cd content up to 0.004 apfu and absence of Fe content. Stibarsen forms up to several mm large aggregates mainly in association with arsenic I, which characteristically contain large amount of Sb arsenic grains. Its empirical formula is Sb0.91As1.09. Silver was found in form of wires and bush like aggregates (8th level). Silver is non-homogenous which is induced mainly by the Hg contents to 3.36 wt. % (0.02 apfu) and also by Sb content to 1.19 wt. % (0.01 apfu). The vertical zonality probably formed by late hydrothermal solutions was found on this vein. Hydrothermal solutions dissolved primary mineralization especially in lower parts of the vein and the crystallization of younger mineral phases followed. These processes gave rise to rich occurrences of native silver and Hg silver together with pyrargyrite and allargentum around and above the 8th level, while the older Sb arsenic accompanied by dyscrasite and regenerated miargyrite predominate around the 7th level.

230Skacha_Vol.no20_Issueno2.pdf

230_254 ABS SkachaSejkoraKnizekSlepickaLitochlebJebava_H14F3.pdf