Barrick Gold has flagged the possible sale of its Plutonic mine in Western Australia, along with its three Yilgarn mines, which were put up for sale earlier in the year, as it seeks to slash costs. Gold miners globally have been slashing costs as well as focusing on higher-grade reserves as they seek to quickly stem a sharp slide in revenue following the slump in the gold price over the past three quarters. When releasing its June quarter earnings overnight, Barrick disclosed an $US8.6 billion ($A9.6 billion) loss, due largely to $US8.7 billion of asset write-downs on the plunge in the gold price. Reviewing its portfolio of gold mines, Barrick said it would focus on four mines, which generate 60 per cent of output and which have an all-in production cost of less than $US700 an ounce of gold produced. At other mines, a range of initiatives are being pursued that will either see production changes or divestment. At the large Porgera in Papua New Guinea, for example, it said it will "evaluate mine-plan changes and explore other alternatives." With its Australian mines - Plutonic and Yilgarn - it said it will "optimise the mine plans and/or divest" as it seeks to optimise cashflows at all mines. "A process to divest certain Australian assets is well advanced," Barrick told investors when releasing June quarter earnings overnight. In the quarter, its mines in Australia and the Pacific produced 0.47 million ounces of gold, costing $US1,033 an ounce, with costs distorted by Porgera, its largest mine in the region, producing 0.12 million ounces at a high costs of $US1306 an ounce. "We continue to expect full-year production to be in the range of 1.70-1.85 million ounces and now expect [all-in cost] to be in the range of $US1100-$1200 per ounce, lower than our previous range of $US1200-$1300 per ounce," it said. The decline in the Australian dollar in foreign exchange trading also assisted in reducing costs, it said.