Finding of authigenous native gold in Novobobrovskoe rare-metal and rare-earth deposit (Chetlassky kamen, Middle Timan)

For the first time the mineralogical characteristics of fine native gold from ores of Novobobrovskoe rare-metal and rare earth deposit are presented. We studied the gold using microprobe technique and Raman spectroscopy. The gold finding in the ore (angular particle with dimensions 0.3 ´ 0.2 ´ 0.1 mm) is characterized by increased concentrations of silver (16-31 wt. % Ag), gradually increased to the periphery. Minerals of ore associations, gothite, monazite and quartz, were found on the surface of gold cuts by means of electron microprobe analysis and Raman spectroscopy. These minerals are typical for the ores of Novobobrovskoe deposit. Determined levels of concentration of impurity elements in monazite - cerium, neodymium, lanthanum, praseodymium, samarium (dominants: cerium - close to two tens wt. % Ce2O3 and neodymium - first ten wt. % Nd2O3), thorium (6-8 wt. % ThO2) и strontium (2-3 wt. % SrO) are identical for chemical contents of monazites of this deposit.