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 Kencana mineralised system is a complex intersecting network of structures consisting of well-developed epithermal vein zones (K1 and K2) and link structures. The (K1) Kencana deposit was discovered in 2002 and gold production commenced in early 2006. Since June 2009, production has been mainly from the Kencana K2 and K-Link systems as well as from the K1 orebody.

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.

The processing plant at Gosowong, which has a capacity of up to 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 smelted to produce gold and silver doré. The gold doré is then refined at Logam Mulia which is owned by Newcrest’s joint venture partner PT Aneka Tambang.