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The Hwini-Butre and Benso deposits are located in the Western Region of Ghana, south of Golden Star’s Wassa mine.
The feasibility study for the development of Hwini-Butre and Benso was completed in May 2007 and project development commenced immediately following receipt of environmental approvals in October 2007. The feasibility study work is summarized in our National Instrument 43-101, of the Canadian Securities Administration, Technical Report.
The underlying concept for the feasibility study and development of the Hwini-Butre and Benso projects is to provide a source of high grade mill feed to the Wassa CIL processing plant. Construction for the haul road commenced in October 2007 with pre-stripping and ore mining at Benso anticipated to commence in the third quarter of 2008. The higher grade deposits on the Hwini-Butre concession, south of Benso, are scheduled to be mined following the completion of the 30 kilometer haul road extension in 2009.
Metallurgical test work has indicated that the Hwini-Butre and Benso ore is harder than the Wassa ore which should result in higher milling costs and a slightly reduced throughput. The Wassa processing plant will be slightly modifided to increase total residence time and achieve design metallurgical recoveries.
The HBB concessions lie along the southeastern flank of the Birimian-aged (lower Proterozoic) Ashanti Belt, along the same structure as Wassa. The southwestern part of the Hwini-Butre concession covers Mpohor Complex, a syn-volcanic mafic intrusive that is bound to the east and north by the Butre volcanic sequence. The Mpohor Complex is a polyphase intrusion with compositions ranging from gabbroic to granophyric, with intermediate phases such as diorite and granodiorite. The Butre volcanic sequence, which also underlies the South Benso concession further north, mostly comprises volcanic flows with minor meta-sediment horizons. The main regional structural orientation trends northeasterly but extensive north to northwest trending cross-cutting fracture systems are also well developed. The latter host much of the mineralization in the district, with vein systems at Dabokrom, Father Brown, Adoikrom, the Subriso zones and Amantin located within or marginal to the Mpohor Complex.
Mineralization on the Hwini-Butre concession is typically associated with shallow east-dipping narrow quartz veins and their associated sericitic alteration halos, with coarse free gold associated with sulfides and as specks within the quartz veins and altered host rocks. In contrast, mineralilzation at Subriso West and Central Subriso forms a series of relatively steep dipping, north-trending zones characterized by strong shearing and pervasive silica replacement with local silica flooding and only minor thin quartz veining.
