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2006 Exploration Program
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
Checking core samples at Twangiza |
Hilltop view of the Twangiza field camp |
An aggressive drilling program is planned for Twangiza in 2006 |
Channel Sampling at Twangiza |
Trench Photos Corresponding to the Press Release of January 17, 2006
Trench TWT1 |
Trench TWT2 |
Maps
December 2006
Twangiza Project Drill Hole Locations
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November 2006
Twangiza Project Drill Hole Locations
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July 2006
Twangiza Project Drill Hole Locations
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May 2006
Soil and Geochemistry and Trench Results
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2005
Additional Exploration Potential |
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