All economic mineralisation at Gosowong is of low sulphidation epithermal type occurring as mineralised fault systems resulting from high temperature gold and silver bearing hydrothermal fluids. The ore shoots are narrow and approximately planar although irregular and complex in local detail. The deposits are relatively moderate to low in dip averaging around 40-50 degrees in the Kencana – Gosowong structural corridor and sub-vertical in the Toguraci corridor. Silver to gold ratio in the ore is approximately 1:1.

The Gosowong operation comprises the Kencana and Toguraci underground mines.

Kencana Mine is located 1 km south of the original Gosowong Pit. It is the third mine to be developed by the joint venture at the Gosowong site and the first underground mine. Underground development of the Kencana mine commenced in February 2005, with the first underground ore mined in March 2006. Gosowong currently encompasses the Kencana and Toguraci underground mines. The Kencana
underground mine utilises predominantly underhand cut-and-fill with some long hole stoping, while
the Toguraci underground mine uses long hole stoping and overhand cut-and-fill.

Processing technologies at the Mill include:
• Gravity separation
• Counter current decantation (CCD)
• Agitated tank leaching
• Merrill Crowe zinc precipitation
• Cyanide leaching

The processing plant at Gosowong, which has a capacity of 800,000 tonnes per year, comprises a
primary jaw crusher followed by a SAG and ball mill circuit and a Vertimill circuit. The ore then
undergoes a conventional cyanide leaching process. Gold and silver is recovered from the cyanide
solution using the Merrill-Crowe Zinc Precipitation Process and is then smelted to produce gold and
silver ore. The gold ore is then refined at Logan Mulia which is owned by PT Aneka Tambang.