Autigenic mineralization in river placers as a natural scientific phenomenon

New data on autigenic mineralization in the Urals gold-platinum river placers, presented by gold films passively growing on fragmental golds, and kelifite edges metasomatically replacing them is given. Gold films possess spongy microstructure, as an impurity to gold in them act phases of mixed Au-Pb composition, native copper, Au-bearing galenite and Au-Ag-Pb-Fe hydroxylbromides revealed for the first time. Zone kelifite edges are built of continuously varying in composition Au-Pb substitutional solid solutions formed as a result of ionic exchange of gold by lead on the surface of clastic golds and subsequent diffusion metasomatism. At that overwhelming part of native-metal phases falls within the area Au2Pb-Au3Pb for which the mineral hunchunite is dated.