The Talang Santo deposit is an epithermal gold / silver deposit. Mineralisation is hosted within a vein system of brecciated parallel quartz veins with a dominantly clay supported matrix which also contains clay altered volcanic fragments.

The geology of the Talang Santo project area consists predominantly of mid-Miocene volcanic units, comprising andesitic volcanic breccia and andesite lava grading upwards into andesitic tuff with parallel lamination sediment structures. These rocks are intruded by both plagioclase andesite porphyry and hornblende andesite porphyry.

A dextral, strike-slip fault which hosts the gold-bearing vein epithermal veins at Talang Santo trends west-northwest, whilst the north-northeast structures observed in the mine area have resulted from the intrusion of the andesitic porphyry. Low-angle quartz veins dipping to north-northeast are potentially the result of hydrothermal fluid flow following fractures related to a dilatational compressive event. It is anticipated that gold / silver precipitation occurred when the regional tectonic field was in compressive relaxation.

The Talang Santo gold / silver deposit is centred on an extensive epithermal quartz vein system (and associated wall rock alteration), which has been identified over a strike of approximately fourteen hundred metres.

Drilling has identified a semi-regular, parallel quartz vein system, dipping at approximately fifty degrees to the eastnortheast, with several parallel mineralised structures and sub-parallel mineralised splays also observed. The mineralised veins vary in width from sub-one metre to five metres with an average width of approximately one and a half metres. The system effectively remains open in all directions.

The Talang Santo vein system:
Mawi Vein
The main mineralised entity, the Mawi vein is brecciated parallel quartz veins with a dominantly clay supported matrix which also contains clay altered volcanic fragment. The veins outcrops and are typically banded and brecciated.

Splay vein
The splay vein is a lower-grade gold bearing vein, which sees an increase in tenor at its intersection with the Mawi vein where it also results in a deflection of the Mawi vein strike.

Silver Vein
The Silver vein outcrops to the south from Mawi vein, and joins with it at West Santo. Drilling has indicted that commercial grades are attainted where the Silver Vein merges with the Mawi vein.

Mineralisation.
Epithermal gold-silver quartz vein mineralisation has been identified at Talang Santo over a strike length of fourteen hundred metres and to an explored depth of approximately four hundred metres below surface.

High-grade gold and silver was detected in the Mawi vein in layers of banded quartz veins and in brecciated quartzaltered wall rock. Massive white quartz and chalcedony is generally low in gold and silver content.

Propylitic alteration prominently occurs at the periphery of the veins. With clay and silica alteration displayed close to the veins structures.

Production of gold and silver commenced from the Talang Santo underground mine in July 2014 (sub-level stoping and room-and-pillar mining methods). Underground mining occurred up until 2018.

In November 2018, Talang Santo open pit has started. The Talang Santo open pit is similar to the Way Linggo open pit in that the mine will be located on the previously mined underground ore body. The open pit will extract upper levels of the remnant ore pillars and areas of the mine that were left behind, due to the mining method employed in the underground mine. It is estimated that there is 50% of the orebody remaining in the area which will be the subject of the open pit.

Planned mining in the Talang Santo open pit was completed in April 2020.

Way Linggo Process Plant:
• Free milling ore (non-refractory)
• Crushing > milling > leach >merrill-crowe > smelting > gold & silver dore
• Gold and silver refined at refinery in Java, Indonesia.