Geology of the Rincon de Garcia gold deposit, Nicaragua

The Rincon de Garcia gold deposit is located in the El Limon Mining District in north-western Nicaragua. The gold mineralization is hosted in quartz veins in tertiary volcanic rocks of andesitic composition. The gold occurs in quartzose bands as free electrum grains at grain boundaries or in poly phase mineral aggregates of jalpaite, achantite, native silver and chalcopyrite. The size of the electrum particles is generally in the range of 10-25 microns. The vein system is structurally complex and comprises both sub vertical and moderately dipping veins. The veins are associated with zones of hydrothermal alternation and spatially related to dykes of intermediate to basic composition. Regionally, the deposit is situated in the eastern part of the Nicaragua depression, a zone of extensional tectonics which can be traced from the Atlantic coast in Costa Rica to the Fonseca gulf between Nicaragua and El Salvador. The area surrounding the deposit is dominated by a sequence of volcanic rocks ranging from rhyolites to basaltic andesite in composition. (author)