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The most recent technical report with respect to the Twangiza Property that have been filed by Banro on SEDAR is the "Preliminary Assessment NI 43-101 Technical Report, Twangiza Gold Project, South Kivu Province, Democratic Republic of Congo," dated September 13, 2007 and which was prepared under the supervision of James Hollywood, Managing Director of SENET. A copy of this report may be accessed at www.sedar.com or by clicking on the link below
History
The Twangiza gold deposit was discovered by Miniere des Grande Lac (MGL) in the 1950s. The company followed the occurrence of alluvial gold deposits upstream from the Mwana River to the present-day Twangiza deposit. MGL tested the deposit through 8,200 metres of trenching and 12,100 metres of adits on seven levels, collecting a total of 17,400 samples. In the mid-1970s, Charter Consolidated undertook detailed exploration, including the excavation of numerous close-spaced adits into the mineralized zone. In 1996, Banro acquired control of the Twangiza Property, and during the following year, undertook a US $9 million exploration program, which included 10,490 line-kilometres of airborne geophysics, 1,613 samples from 16 adits, and 8,577 drill core samples from 9,122 metres of core drilling along 800 metres of strike. This represents less than 20 percent of the identified mineralized trend. Independent consultants, CME Consulting Ltd., determined in a technical report prepared for Banro in April 2003 that all fieldwork undertaken during Banro's 1997-1998 exploration program was compliant with National Instrument 43-101 and provided updated mineral resource estimates. On September 28, 2006, Banro issued further updated mineral resource estimates, which increased Inferred Resources by 230%. Resources were again updated on June 13, 2007 with the discovery of the Twangiza North deposit. Mineralization The Twangiza area is underlain by sediments of Proterozoic age that have been intruded by porphyry sills, folded into a series of broad anticlines and synclines and subjected to very low-grade metamorphism. The gold mineralization at the Main Twangiza deposit is hosted within mudstones, siltstones, greywackes and porphyries along the crest of a major anticlinal structure. Gold mineralization is of hydrothermal origin and is associated with sulfides which occur in quartz-carbonate veins, and disseminations throughout the host rocks. Unlike the Twangiza Main deposit, the mineralization at Twangiza North is associated predominantly with feldspar porphyry sills that have intruded westerly dipping shales and siltstones, with the mineralization in this lithology being non-refractory. This mineralization is open at depth and to the north where recent regolith mapping has indicated that the gold-in-soil anomalism has been masked by recent colluvial and alluvium material. Other significant gold occurrences on Banro's Twangiza's concessions include Tshondo and Mufwa; these occurrences will be examined as part of the current exploration program. Independent consultants, CME Consulting Ltd., determined in a report prepared for Banro in April 2003 that all fieldwork undertaken during Banro's 1997-1998 exploration program was compliant with NI 43-101 and provided an updated mineral resource. This mineral resource was subsequently updated in September 2006, January 2007, June 2007 and January 2008 and is set out in the table below, using a 1 g/t cutoff.
2007 Exploration Program, Maps and Photographs 2006 Exploration Program, Maps and Photographs 2005 Exploration Program, Maps and Photographs Maps
2005 Exploration Program
October / November 2005
Maps
The year proved to be exceptionally rewarding for Banro's Twangiza project. Following three months of intense groundwork, the Company began drilling in February 2006, focusing primarily on the southern part of the Twangiza mineralized trend, with the goal of increasing the total resource base and upgrading the Inferred resource ounces. By year-end, the four core rigs operating at Twangiza had completed 71 core holes (71,065 metres). Throughout the year, this ongoing core drilling program continued to intersect wide, multiple zones of gold mineralization within the Main Twangiza deposit where previous drilling was too widely spaced to outline higher confidence mineral resources. The results of this successful program enabled the Company to increase and upgrade the Twangiza resource base in September 2006 and again in January 2007. Total resources at Twangiza grew by 75% over the year, with Measured and Indicated Resources increasing by 49% to 3.009 million ounces of gold. The Inferred Resource at January 31, 2007 was 2.63 million ounces of gold. The Company views the significant increase in the total resource base at Twangiza as exceptionally encouraging and demonstrates the potential for this project to develop into a major open pit gold mining operation with a significant component being in good grade, near surface, oxide and transitional material. In addition to the ongoing drilling of the Main Twangiza deposit, results from two boreholes drilled 1,400 metres to the north between the Kashegeshe and Lukungurhi workings indicated good potential for the delineation of additional resources outside the Main Twangiza deposit. This new mineralized zone comprises a sedimentary package of mudstone, carbonaceous mudstone and siltstone that have been intruded by feldspar porphyry sills. Sulphide mineralization consists of disseminated and massive, pyrite and arsenopyrite. Surface structural mapping indicates a NNW-SSE bedding plane trend which is similar in orientation to the Main Twangiza deposit. The more southerly of these holes, located 150 metres north of the Lukungurhi workings, is interpreted as having been drilled into the hanging wall of the mineralized trend. Further drilling is being undertaken to determine the resource potential of this new mineralized zone. In November, the Company also announced preliminary metallurgical test results for the Twangiza project. Eleven composite drill hole samples of approximately 10 kilograms each were submitted to the SGS Lakefield laboratory in South Africa for initial diagnostic leaching testwork to establish the gold-mineral association within oxide, transitional and fresh rock materials. The diagnostic testwork procedure involved the sequential solubilizing of the least-stable minerals via various pre-treatments (cyanidation, hydrochloric and nitric acid) and extraction of the associated gold by cyanidation/CIL. Results for the four oxide samples gave recoverable gold by CIL (carbon-in-leach) processing of between 88.92% and 95.63%. For the four transitional material samples, expected recoverable gold by carbon-in-leach processing varied between 27.33% and 90.01%. The three fresh rock samples gave expected recoverable gold by carbon-in-leach processing of between 42.19% and 61.96%. These preliminary results demonstrate the high metallurgical recoveries of the oxide material at Twangiza. Further submission of samples for mineralogical and leaching testwork are being undertaken for the transitional material to investigate the wide variation in metallurgical recoveries, to better define the leach characteristics of this material type and to optimize metallurgical recoveries. Additional mineralogical and metallurgical testwork is being conducted on the fresh rock material to identify processing methods for optimizing metallurgical recoveries. Photos
Trench Photos Corresponding to the Press Release of January 17, 2006
Maps December 2006
November 2006
July 2006
May 2006
2005
Among the highlights of the 2007 exploration program was the discovery and expansion of the gold deposit at Twangiza North, a new trend of approximately 2,500 metres in length, extending directly north from the Twangiza Main deposit. The full Twangiza trend now consists of 3,200 metres of gold mineralization. This new discovery was a result of drilling out a +100 ppb gold-in-soil anomaly that has a strike length of approximately 1.8 kilometres. Unlike the gold mineralization at the Twangiza Main deposit, which is hosted predominantly in shales and siltstones, the mineralization at Twangiza North is associated predominantly with feldspar porphyry sills that have intruded westerly dipping sediments (shales and siltstones). The mineralization in this lithology is non-refractory and open at depth and to the north. The Twangiza North discovery, together with continued infill drilling along the Twangiza Main deposit, led to a significant increase in resources at the property during the year, with Measured and Indicated Mineral Resources at Twangiza as a whole increasing by 29% to 3,872,000 ounces of gold (53,629,000 tonnes grading 2.25 g/t Au). The Inferred Mineral Resource at Twangiza increased slightly to 2,705,000 ounces of gold (46,188,000 tonnes grading 1.82 g/t Au). The exploration progress achieved at Twangiza in 2007 resulted from an intensive drilling program of 120 core holes totaling 26,411 metres, with the primary objective being to upgrade and increase the previously defined Inferred Mineral Resource. Between the resumption of drilling in February 2006 and year-end 2007, Banro completed a total of 191 core holes totalling 43,476 metres at Twangiza. Four drill rigs are currently deployed at the Twangiza property, with additional rigs to be mobilized in 2008. 2007 also saw Banro begin exploration of the Twangiza property outside the main trend. The Company established a new exploration camp at the major artisanal site at Mufwa, situated 13 kilometres northwest of the Twangiza Main deposit, and initiated field work in other target areas including the promising artisanal workings at Tshondo. Additional rigs are being mobilized to Twangiza so this new prospect can also be drilled during the coming months once groundwork has been completed. LIDAR, airborne magnetic and radiometric surveys were also completed of the entire Twangiza property; to date serveral promising new targets have been identified for follow-up work. Preliminary Assessment In July 2007, the Company announced the results of a preliminary assessment (scoping study) of Twangiza. This work included the results of evaluations of in pit mineral resources, capital and operating costs, infrastructural requirements and financial modelling. An increased amount of metallurgical testwork was also undertaken to further evaluate the oxide, transitional and sulphide ore types. The significant projections of the Twangiza scoping study included the following:
Photos
Maps September 2007
May 2007
January 2007
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Having expanded Measured and Indicated Resources by 29% in 2007, Banro is pursuing an intensive drilling program through 2008 while working towards year-end completion of a full Feasibility Study. )
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