Journal of

GEOsciences

  (Formerly Journal of the Czech Geological Society)

Original Paper

Andráš, Martin Chovan

Gold incorporation into sulphide minerals from the Tatric Unit, the Western Carpathians, with respect to their chemical composition

Journal of the Czech Geological Society, volume 50 (2005), issue 3-4, 143 - 156

DOI: http://doi.org/10.3190/JCGS.984

Numerous Sb-Au mineralization occurrences and deposits containing gold-bearing sulphides are described from an area of the Tatric Unit in Western Carpathians e.g.: Pezinok, Dúbrava, Jasenie, Nižná Boca, Vyšná Boca etc. It was shown, that arsenopyrite is the main sulphide mineral incorporating invisible gold in its crystal structure. Concentrations of invisible gold in pyrite are not as high as in arsenopyrite. Only if arsenic is present in pyrite in amounts greater than 0.2 wt %, there is significant incorporation of Au in its crystal structure. Gold content in these sulphides ranges from zero up to several hundred ppm. The fine-grained types contain Au concentrations higher by as much as an order of magnitude. This work has demonstrated that Au co-precipitated together with Fe, As and S during the arsenopyrite and pyrite crystallization and was incorporated in sulphide mineral crystals both as native gold and as chemically bound gold. Although As and Au contents in arsenian pyrites and arsenopyrites vary from sample to sample, there is a positive correlation between Au and As. The covariance in As and An indicates that they were transported by the same solutions and that the same geochemical processes led to their removal from solution. An is predominantly concentrated within As-rich zones of gold-bearing sulphides.