Sojitz Corporation and Nittetsu Mining Co., Ltd. have obtained a prospecting license in the South Moune area, Moune District, Vientiane province, Lao People's Democratic Republic and started exploration activity in 2009. The South Moune area is located 100 km west of Vientiane and this area is included in the Loei belt which is known as a high copper potential area based on the regional geology. Several campaigns of field works have been conducted from December 2009 to February 2014 by Japan Oil, Gas and Metals National Corporation (JOGMEC), Sojitz Corporation and Nittetsu Mining Co., Ltd. and finally several copper mineralized zones were newly discovered and they were thought to have a potentiality for developing copper mine in the future.
Geochemical survey and preliminary geological survey were carried out for the whole area of the prospecting license (226.25 km²) and, after these surface surveys, three copper occurrences such as Phu Sarana, Phu Pa Nyang, Phu Pa Khii (in total 7.12 km²) were picked up based on the data of geological survey and remarkable copper geochemical anomalies. For these three occurrences, grid soil geochemical survey, trench survey and geophysical survey (TDIP method) were also conducted and, based on the data of these surface surveys, the targets for the drilling survey were selected and the drilling survey for these copper occurrences was commenced in November 2011. The drilling survey of total 51 holes (total length: 13,933.60 m) were carried out until February 2014. Several remarkable mineralized zones were observed in the Phu Sarana and Phu Pa Nyang and mineralized zones have chalcopyrite, bornite and pyrite which associated with quartz-calcite veinlets and dissemination in black mudstone. Considering the copper mineralization in the Phu Sarana and Phu Pa Nyang, copper mineralized zones are closely related to the black mudstone and there is a possibility which indicates that the presence of the black mudstone played an important role in forming copper mineralized zones.
The mineralization type is thought to be the volcanogenic massive sulfide (VMS) deposit and the basalts which are associated with copper mineralization show the petrochemical characteristics of the back-arc basin basalt. However, comparing with the data of similar type of VMS deposits, the mineralization of this area is characterized by the very low grade of lead and zinc and the lack of pyrrhotite.
Based on the analytical data of the drill cores, grade calculation and resource estimation have been carried out by using the 3D mining software MAPTEK VULCAN. Estimated resource in the Phu Sarana is calculated as approximately 2.3 million tons, average grade is 1.97 % Cu (cut off:1.0 % Cu).
At the present stage, the extension of the copper mineralized zones has not yet confirmed and it is thought that a scout drilling survey in the surrounding areas to identify the new mineralized zones must be needed to increase the resources for future development.