Vancouver — Some eight years after gaining a foothold in the politically unstable but mineral-rich Democratric Republic of Congo and five years since the government took its exploration projects away,
Situated some 35 km west of the Burundi border and 150 km south of Goma, the 930-sq.-km property has an exploration history dating back to 1957, when Miniere des Grande Lacs (MGL) followed the occurrence of alluvial gold deposits upstream from the Mwana River to the deposit. In total, more than 8,200 metres of trenching and 12,000 metres of adits on seven levels were completed before Banro entered the scene in 1996. The junior went on to complete 10,490 line-km of airborne geophysics and 9,122 metres of diamond drilling.
Shortly after completing the work in 1998, this project and three others held by Banro were expropriated by Laurent Kabila’s regime in the wake of civil war. Banro immediately launched a US$1-billion lawsuit, but it was not until earlier this year that, with a peace accord in hand, a new transitional government led by President Joseph Kabila returned the junior’s mining assets.
Discussions are under way with the government for resuming exploration of Banro’s four projects (Twangiza, Kamituga, Lugushwa and Namoya), and the junior has hired CME Consulting to update the resource at Twangiza.
Using a cutoff of 0.5 gram gold per tonne, the oxide portion of the desposit hosts a measured and indicated resource of 6 million tonnes grading 3.17 grams gold per tonne, plus an inferred resource of 3.5 million tonnes grading 2.62 grams gold. In the sulphide portion, the measured and indicated resource amounts to 48.4 million tonnes grading 1.26 gram gold, plus 35.7 million tonnes grading 1.19 grams gold in the inferred category. Based on the study, the measured and indicated resource holds some 2.6 million ounces of contained gold, whereas the inferred portion contains 1.6 million oz.
At a 0.5-gram cutoff, an estimated 1.3 million tonnes of the oxide resource (measured and indicated) were determined to have been removed since 1998.
Increasing the cutoff to 2 grams gold, the measured and indicated resource for the oxide material comes in at 4 million tonnes grading 3.98 grams gold, plus an inferred resource of 2 million tonnes grading 3.62 grams gold. The sulphide section rings in at 6.7 million tonnes grading 2.81 grams gold for the measured and indicated portion and 4.2 million tonnes grading 2.6 grams gold sitting in the inferred section.
The 800-metre-long deposit is hosted in a relatively unaltered, folded sedimentary sequence of mudstone, siltstone and greywacke that have been intruded by an intercalated sequence of altered intrusive sills. The intrusive sills comprise a mafic porphyry phase and a feldspar porphyry phase. The folding of the anticlinal structure, which is home to the deposit, resulted in fracturing perpendicular to bedding and along the anticline axis. At the same time, east-west-trending left-lateral faults dissected the anticline. Ascending hydrothermal fluids were influenced by the east-west faults and bedding planes, and as a result, gold-bearing zones formed as crescent-shaped lenses of mineralization in the upper side of the sills.
Gold occurs with sulphide mineralization in albite-ankerite and dolomite-quartz veins and with disseminated sulphides mainly in the albite-altered sills and sediments. Drill Intersections range from less than 1 metre grading 3.1 grams gold up to 197 metres grading 3.49 grams gold.
Meanwhile, Banro has identified several magnetic geophysical anomalies north and south of the deposit. These are coincidental with gold showings over a 38-sq.-km area along the Twangiza trend. Grab samples collected by the company returned up to 54.79 grams gold, while channel samples yielded up to 15.43 grams gold over 2 metres.
With stability returning to the region, Banro is planning a program of geological mapping and rock and soil sampling, leading to the diamond drilling of the priority targets.
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