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 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.
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