Supergene Gold Mobility: A Textural and Geochemical Study from Gold Placers in Southern New Zealand
Donna M. Falconer, Dave Craw, 2009. "Supergene Gold Mobility: A Textural and Geochemical Study from Gold Placers in Southern New Zealand", Supergene Environments, Processes, and Products, Spencer R. Titley
Download citation file:
Scanning electron microscopy was used to observe a variety of gold remobilization textures and authigenic gold overgrowths on detrital gold particles associated with quartz pebble conglomerates (QPC) from two localities in eastern Southland, New Zealand. Gold spheroids, spheroids with budlike protrusions, polyspheroidal aggregates, budded mass structures, and pseudohexagonal plates are common on detrital gold particles at these two sites. There has been no anthropogenic introduction of mercury or amalgam at either site. Some gold precipitation textures can be distinguished from some gold dissolution textures. Precipitation textures are characterized by surface textures and pure gold rims that occur on the outermost margin of sharply defined silver (± mercury)-depleted rims in most detrital particles. In contrast, dissolution textures are characterized by varying degrees of dissolution occurring preferentially along subgrain boundaries, thereby revealing the polycrystalline makeup of placer gold. Surface textures reflect a close association between gold precipitation and gold dissolution which may lead to the ambiguity inherent in interpreting gold-remobilization textures from placer environments.