Batu Hijau

Other Names:
District: Sumbawa Island
Commodities :   Copper, Gold

The Batu Hijau porphyry copper-gold orebody is located on the island of Sumbawa in the Sunda-Banda Arc, Indonesia. Mineralisation occurs in the central stock of a tonalite intrusive complex, and in diorite and volcanic wallrocks. 

The central stock has associated intense pervasive potassic alteration that contains most of the higher grade mineralisation. This merges outwards into an extensive propylitic zone. Both of these zones are over-printed by widespread intermediate-argillic and minor phyllic and albite alteration. Argillic and advanced-argillic assemblages occur near surface. Copper and gold are largely hosted by quartz stockworks, but also as disseminations. Chalcopyrite and bornite are the main ore minerals. 

Pit reserves as of December 2002 were 920 mt @ 0.55% Cu, 0.42 g/t Au

(Source: Newmont Indonesia Ltd.,  December 2002)