Heruga is a copper-gold porphyry deposit that is located at the southern end of the Oyu Tolgoi mining complex in southern Mongolia. The project is approximately 570 km south of the capital city of Ulaanbaatar and 80 km north of the border with China, and lies within the eastern end of the Paleozoic Tuva Mongol Arc. It is managed by Oyu Tolgoi LLC, a subsidiary of Turquoise Hill Resources and the Government of Mongolia.
The Heruga deposit differs from the three other Oyu Tolgoi deposits (Oyut, Hugo North, and Hugo South) in that it is slightly enriched in molybdenum. This forms a molybdenum-rich cap at higher levels overlying gold-copper mineralization at depth.
Underground development is underway at the Hugo North deposit and although Heruga is currently outside of the mine plan, it is included in the Alternative Production Cases in a 2016 Technical Report. It is expected to be mined in later phases by underground panel caving methods.
The Heruga Deposit has an Inferred Mineral Resource of 1,816 Mt containing 0.39% Cu, 0.4 g/t Au, 1.4 g/t Ag, and 0.01% Mo. The resources are effective as at Dec. 31, 2015 and use a 0.37% CuEq cut-off grade.
A Preliminary Economic Assessment was released evaluating the inclusion of the Heruga deposit into an overall mine plan with the Hugo North Extension Lift 1.
Entrée is currently working on an updated Technical Report, which will include a PEA on the Heruga deposit. Amec Foster Wheeler Americas Limited has completed its initial data review, and has commenced work on the updated report. It is expected to be completed in January 2018.