Contributions to the Study of the Alluvial Gold from Valea Pianului Area (Alba District)

Contributions to the Study of the Alluvial Gold from Valea Pianului Area (Alba District). Pianu de Sus area (Alba district) is located in the north-eastern part of the Sebes Mountains. The region consists of metamorphic (Sebes-Lotru group), magmatic (granites and quartziferous porphyries and pegmatites) and sedimentary deposits (Senonian, Neogene and Quaternary age). Granulometric studies, separations of the heavy fractions, optic and electronic microscopic investigations were performed on the alluvial deposits and detritic sedimentary formations. The analysed gold shows tipical morphology for two grains types: primary and secondary. From a chemical point of view was evidenced electron microprobe The chemical analyses, performed by using electron microprobe, shows a high amount of gold and silver.