Mineral Resource
Banro's Measured & Indicated (M&I) Mineral Resource has grown to 10.18Moz, an increase of 41%, and Inferred Mineral Resources have grown to 7.01Moz, an increase of 56%, this taking into account depletion at the Twangiza Gold Mine. The growth in the Mineral Resource is attributed to some changes in economic assumptions, which resulted in only a 22% increase of the Mineral Resource, although the main increase was as a result of significant drilling intersections. The Resource estimate discussed in this press release consists of insitu Mineral Resources at a 0.4 g/t Au cut-off falling within a US$2,000 per ounce (2011: US$1,700 per ounce) optimized pit shell.
The underground Mineral Resources at Kamituga are those situated below the Mobale open pit, estimated using historical underground information at a cut-off grade of 1.5 g/t Au. The Mineral Resource estimates for Kamituga were prepared by SRK (UK) using historical data and were included in the February 2005 NI 43-101 technical report prepared by SRK (UK) for Banro. These estimates have not been updated. Banro has since 2011 carried out extensive exploration including some amount of drilling to verify the historical results. This work will be continued during 2013 for an updated estimate for Kamituga to be undertaken by December 2013.
The grade tonnage curve for the Namoya In-pit M&I Mineral Resources is illustrated in Figure 2, and demonstrates that the Namoya project can be mined at a significantly higher grade than the Resource grade without impacting significantly on the contained gold. This is based on the fact that if one increases the cut-off from 0.5g/t Au to 1.00g/t Au, grades increase from 2.04g/t Au to 2.79g/t Au, with contained gold reducing by only some 12% and could even be increased above 3.0g/t Au without compromising the mine life significantly. This indicates that high-grading the deposit is a feasible option and mine planning could focus on a higher grade, lower tonnage mine design in times of a falling metal market without destroying the economics of the project. The Namoya In-pit M&I Mineral Resources at the various cut-off grades are summarized in Table 3.
Mineral Reserve
The Proven and Probable Mineral Reserve of Twangiza has increased by 36% from 1.13 Moz to 1.54 Moz. This 36% increase of 0.41 Moz, after mining depletion, is primarily a function of delineation drilling at Twangiza West, which resulted in increased confidence of estimated Mineral Resources, and changes in economic assumptions with improved costs from 2011 to 2012. The current open pit Mineral Reserve was estimated using a weighted average breakeven grade of 0.54 g/t Au at a gold price of US$1,500 per ounce (2011: US$1,200 per ounce). Margin dilution and ore loss were included into the estimation of Mineral Reserves. Twangiza stockpile Reserves were calculated at a cut-off grade of 0.75 g/t Au.
TABLE 3: Current In-pit Mineral Resources at Various Cut-off Grades for the Namoya Project
----------------------------------------------------------------------------CUT-OFF GRADE TONNES Av. GRADE GOLD CONTENT(g/t Au) (Mt) (g/t Au) (Moz)----------------------------------------------------------------------------0.50 25.56 2.04 1.67----------------------------------------------------------------------------0.75 20.26 2.41 1.57----------------------------------------------------------------------------1.00 16.24 2.79 1.46----------------------------------------------------------------------------1.25 13.34 3.15 1.35----------------------------------------------------------------------------1.50 10.96 3.54 1.25----------------------------------------------------------------------------1.75 9.18 3.91 1.15----------------------------------------------------------------------------2.00 7.86 4.25 1.07----------------------------------------------------------------------------2.25 6.81 4.58 1.00----------------------------------------------------------------------------2.50 5.93 4.91 0.94----------------------------------------------------------------------------2.75 5.16 5.25 0.87----------------------------------------------------------------------------3.00 4.56 5.56 0.82----------------------------------------------------------------------------
