MORPHOLOGY OF NONRECOVERABLE GOLD IN THE WEATHERED MANTLE

Abstract

We made mass determinations of the morphology and the particle size of non-recoverable gold from weathered mantle developed in Yakutia, the Krasnoyarsk kray and the Urals on gold-sulfide-quartz deposits with finely divided primary gold ore. We started with the minus 100 μm fraction of unconsolidated sediment. Observations were made under the BS-501 scanning electron microscope. To detect gold, we used the preparation procedure that concentrates gold and dissociates the aggregates in which it was buried after coagulating with the accompanying finely divided particles of rock-forming minerals. Gold was identified on the basis of the level of electron absorption, as well as by X-ray spectral analysis, on the basis of the intensity of characteristic AuLα radiation. Such observations allowed us to estimate the fractions of gold dust (50 to 10 μm), finely divided gold (10 to 0.1 μm) and ultrafinely divided gold (< 0.1 μm), the ratios of residual and secondary gold, and the possible mechanisms of gold transfer and redeposition in the supergene alteration zone.