Gold Mineralogy

Gold mineralogical studies, undertaken to assess the mineralogical factors which may influence gold recoveries during heap leach processing, has determined that principal form of gold is fine grained native gold of a high purity, averaging ~97%. The small grain size and high purity of the gold explains the fast leach times achieved in column test work. The mineralogical studies confirm that the Cerro Maricunga gold mineralization is amenable to heap leaching.

The figure below summarizes the characteristics of the gold observed in five samples which were used for column test work. The total percentage of free or liberated gold (light gold coloured bar) and exposed gold (dark gold coloured bar) from 5 composite samples varies from 79% to 89% which compares favourably with the gold recoveries achieved from the five column leach tests noted in the table and by the red lines.

Gold Recoveries

Gold is found dominantly as free grains associated with iron oxides (magnetite) and rock mineral particles. The primary iron mineral is magnetite averaging approximately 4% throughout the deposit. Sulphide minerals are rarely (<0.1%) observed even at depths in excess of 500 metres. Total sulphur content averages 0.2 to 0.5% within the gold zones irrespective of depth.