Batu Hijau is a porphyry copper-gold deposit located on Sumbawa Island in the western Banda Arc of Indonesia. The deposit
has been evaluated from 54000m of drilling in 105 diamond drill holes over a surface area of 1.2km2 and to a depth of 1000m
below surface (412m below sea level). A provisional plan is being evaluated to mine 642 million tonnes at an average grade of
0.61% Cu and 0.55g/t Au (variable cutoff) from an open pit in the higher grade portion of the resource. The deposit is associated with a caic-alkaline intrusive complex that was emplaced in a thick sequence of andesitic pyroclastic
rocks. The oldest and most widespread intrusion is porphyritic to medium-grained, equigranular, quartz hornblende diorite. At
Batu Hijau the western diorite contact zone was intruded by two phases of tonalite. The older tonalite is a stock increasing from
200m diameter at surface to 500m at sea level. It consists of quartz, plagioclase and hornblende phenocrysts set in a
groundmass of similar composition. A younger tonalite intrudes the tonalite stock, quartz and plagioclase phenocrysts are more
abundant and it has a finer groundmass than the older tonalite. Brecciation occurs near the older tonalite contacts but there are
no breccia pipes or late-stage features such as pebbldykes or postmineralisation intrusive rocks.