Preliminary cyanide bottle-roll leach testing on samples of weathered to fresh gold-mineralized quartz vein material from the Sentul West Vein of Arc Exploration’s Trenggalek project in East Java has returned gold extractions averaging 81%.
These initial results suggest that the gold-bearing vein may be amenable to processing by conventional CIP processing methods if a significant gold resource is defined.
Arc has maintained a low-level of exploration activity at Trenggalek while the company considers its options on moving this project forward.
The company recently commissioned the preliminary bottle-roll cyanide-gold leaching test work on drill core material resampled from the West Sentul epithermal gold vein on Sentul prospect in the southeast corner of the IUP. The test work was done by PT Intertek Utama Services at their laboratory in Jakarta.
The test work was done on 52 PQ/HQ-size quarter-core samples taken from seven diamond-core holes drilled on the West Sentul Vein at Sentul in 2010. The samples were selected from 1-metre drill sample intervals within the strongest mineralized segment of West Sentul and represent a range of weathering conditions and gold grades in this
The percentage cyanide-gold leach extraction was calculated by Leached Gold divided by Gold Head Grade. The test-work results show an average cyanide leach extraction of about 81% of the gold present in the 52 samples. Gold extraction results ranged from 26% to 99%. The 16 highest grade samples (>3 g/t Au) showed a gold extraction ranging from 87% to 95%.
Additional drilling and test-work are required to define a potential gold resource and to further assess the metallurgical characteristics of the gold-bearing veins on Sentul prospect.
Arc operates a joint venture with its local Indonesian partner, PT Sumber Mineral Nusantara, who holds the Trenggalek Exploration IUP tenement, in the Southern Mountains of East Java. These mountains comprise an older segment of the Sunda-Banda magmatic arc which hosts the Tumpangpitu porphyry copper-gold about 200km to the east of Trenggalek, and the large Batu Hijau and Elang porphyry copper-gold deposits on Sumbawa Island.
The Trenggalek Exploration IUP tenement is valid until November 2016 and covers an area of about 300sqkm.