There are six defined mineral deposits at the Martabe Gold Mine. Purnama is the largest, and the first to be mined. Mining at the nearby Barani deposit is scheduled to commence soon. These deposits are of a type known as high sulphidation epithermal deposits, and comprise part of a large-scale mineralised district which has the potential to host further gold and gold copper deposits.
As of December 2016, the estimated resource base of Martabe Gold Mine was 7.5 million ounces of gold and 67 million ounces of silver. Meanwhile the reserve base of Martabe Gold Mine was 3.2 million ounces of gold and 29 million ounces of silver.