THE second stage of exploration at the Trenggalek joint venture project in East Java is expected to be completed by May with a budgeted cost of US$1 million. This is focusing on the Singgahan prospect and is being carried out by PT Danusa Tambang Nusantara on behalf of JV partners Arc Exploration and PT Sumber Mineral Nusantara (SMN).


Drilling at the Trenggalek project in the Southern Mountains of East Java.

Danusa, a subsidiary of one of Indonesia’s largest contract miners, is managing and funding exploration work at Trenggalek under an agreement arranged in 2015. The tenement is in the Southern Mountains, in an older segment of the Sunda-Banda magmatic arc.

Scout diamond drilling on Singgahan prospect in the southeast corner of the Trenggalek Exploration IUP was conducted in 2014. The four inclined diamond holes completed a fence of holes across part of an extensive copper-gold-molybdenum soil anomaly and coincident magnetic-high anomaly.

Porphyry-style mineralisation was intersected in these holes which returned multiple low-grade copper-gold-molybdenum intersections. A petrological investigation completed on selected core samples from these holes confirmed the occurrence of porphyry-style veining and alteration, with copper and molybdenum minerals.

Recent mapping in the area has identified porphyry style mineralisation at the surface. A combined Induced Polarisation survey and ground magnetic survey consisting of 19.9km on 13 lines has been completed. These results combined with existing aeromagnetic data and detailed geological mapping have been used to define drill targets for the second phase of Trenggalek exploration by Danusa.

Further ground works, including soil sampling and mapping, have been undertaken in the area of porphyry-style mineralisation exposed at surface at Singgahan.

Preparations for the second phase work include community and local government consultation with an independent geologist engaged to undertake a project review.

The JV has received all results for the 2016 diamond drilling campaign conducted by Danusa at the Sentul and Buluroto epithermal gold veins. The drilling tested for mineralised extensions within the large veins which were previously identified with scout diamond drilling by Arc in 2010/11.

Among the significant results were 1.25 metres from 86.5 metres down-hole @ 4.1 g/t gold; 1.1 metres from 113 metres @ 2.46 g/t; and 1 metre from 217 metres @ 1.03 g/t. All these results were from the Sentul West vein.

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