The Dervish deposit is located 1km to the North of the Carosue Dam processing plant. The ore zone is of considerable width (25-30m) with grades of approximately 3g/t. The open pit provides a low cost mill feed source in close proximity to the processing facilities.
Dervish is hosted by volcaniclastic sandstones, intermediate tuffs and porphyry units. Gold mineralisation is strongly associated with hematite-silica-sericite alteration. The deposit is dominated by the north-west striking footwall domain, which is up to 30m wide. Mineralised structures in the hanging wall are less continuous and typically narrower in width.
The mineralization is terminated to the south by the regionally extensive Osman Fault.
The Dervish open pit was completed in June 2015. Total open pit production totalled 7.38Mt @ 1.49g/t for 352,800oz and performed very well relative to the estimated Mineral Resource and Ore Reserves. Following three stages of open pit mining, an underground exploration portal was established in 2017 with the purpose of completing a vast amount of exploration drilling to define a reserve. Following positive results, the underground production decline was re-commenced in 2018. The deposit is located less than 500m from the Carosue Dam mill. Dervish forms part of the same mineralisation package as Karari and has been offset some 1.5km to the north by the Osman Fault.
Dervish Undergound mines the orebody via a longhole open stoping method from top down with the ore production ramped up to approximately 850kt per annum, and along with Karari forms ‘Carousue Dam Underground’ which provides the majority of the mill feed. Byrnecut is the mining contractor at Dervish, whose fleet currently comprises of 1 Jumbo, 3 LHD’s, 2 Production Drills and 8 trucks.