Trace elements in pyrite from the Petropavlovsk gold–porphyry deposit (Polar Urals): Results of LA-ICP-MS analysis

Resumo

The first study of the pyrite composition from gold deposit in the Urals by the LA-ICP-MS method has been carried out. In the pyrite high contents of Au (up to 49 ppm), Ag (105 ppm), and other micronutrients (As (417 ppm), Ag (105 ppm), Co (2825 ppm), Ni (75 ppm), Cu (1442 ppm), and Zn (19 ppm)) were detected. Furthermore, an increase in the concentrations of trace elements from early to later generations of pyrite (from Py-1 to Py-3) Au, Ag, Te, Sn, Te, and Bi and depletion of Co, As, and Ni have been revealed. Gold is mainly concentrated in the pyrite of the second generation (Py-2) and occurs mostly as an “invisible” form with prevalence of nano-sized particles of native Au, similar in composition to electrum AuAg, as well as Au- and Au–Ag tellurides. The presence in the pyrite of admixtures of Cu, Co, Ni, Pb, As, and Te, possibly favors the entrance of Au into it (up to 5–50 ppm), while in common pyrite, poor in the mentioned impurities, the gold content is <1 ppm.