Podrobnosti záznamu

Název
    Arsenopyrite and As-bearing pyrite from the Roudný deposit, Bohemian Massif
Údaj o odpovědnosti
    J. Zachariáš, Jiří Frýda, B. Paterová, Martin Mihaljevič
Autor
    Frýda, Jiří, 1961-
    Mihaljevič, Martin, 1965-
    Paterová, B.
    Zachariáš, Jiří
Jazyk
    anglicky
Zdrojový dokument - seriál
    Mineralogical magazine
Svazek/č.
    Vol. 68, no. 1
Strany
    p. 31-46
Rok
    2004
Poznámky
    1 obr., 1 fot., 6 diagr.
    Bibliografie na s. 44-46
    il.
    Zkr. název ser.: Mineral. Mag.
Klasifikační znak
    549
    553.3/.4
Skupina konspektu
    549
    553
Předmětová skupina
    arzén
    arzenopyrit
    blanická brázda
    chemismus minerálů
    hydrotermální podmínky
    moldanubikum jižních a jihovýchodních Čech
    pyrit
    rudy Au
    substituce
    zlato
    zonálnost krystalu
Geografické jméno
    ČR-Čechy
    Roudný (Benešov, Votice)
Klíčové slovo
    Arsenopyrite
    As-bearing
    Bohemian
    Deposit
    Massif
    Pyrite
    Roudný
Abstrakt (anglicky)
   The major- and trace-element chemistry of pyrite and arsenopyrite from the mesothermal Roudný gold deposits was studied by electron microprobe and laser ablation ICP-MS techniques. In total, four generations of pyrite and two of arsenopyrite were distinguished. The pyrite is enriched in As through an Fe (AsxSi1-x)2 substitution mechanism. The As-rich zones of pyrite-2 (up to 4.5 wt.per cent As) are also enriched in gold (up to 20 ppm), lead (commonly up to 220 ppm, exceptionally up to 1500 ppm) and antimony (commonly <600 ppm, rarely up to 1350 ppm). Positive correlation of As and Au in the studied pyrites is not coupled with an Fe deficiency, in contrast to Au-rich As-bearing pyrites in Carlin-type gold deposits. The As-rich pyrite-2 coprecipitated with the Sb-rich (1-4.2 wt.per cent) and Au-rich (40-150 ppm) arsenopyrite-1. The younger arsenopyrite-2 is significantly less enriched in these elements (0-70 ppm of Au).
   The chemical zonality of pyrites in the Roudný gold deposits reflects the chemical evolution of ore-bearing fluids that are not observed in any other mineral phases. The data available suggest relatively high activity of sulphur and low activities of arsenic and gold during crystallization of the older pyrite generation (pyrite-1). Later, after particular dissolution of pyrite-1, Au-rich As-bearing pyrite-2 and arsenopyrite precipitated. These facts suggest a marked increase in the arsenic and gold activities in ore-bearing fluids. The As-content of pyrite-2 decreases in an oscillatory manner from the core to the rim, reflecting changes in the As activity or/and in the P-T conditions. The As-bearing pyrites were formed at temperatures of at least 320-330°C, based on arsenopyrite thermometers and fluid inclusion data
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    25. 3. 2008
Datum importu
    8. 8. 2012