Aura Minerals Inc.
TSX : ORA

Aura Minerals Inc.

November 10, 2011 18:43 ET

Aura Minerals Announces Updated Resource and Reserve Estimates for Brazilian Gold Mines

VANCOUVER, BRITISH COLUMBIA--(Marketwire - Nov. 10, 2011) - Aura Minerals Inc. (TSX:ORA) ("Aura Minerals" or the "Company") announces updated resource and reserve estimates for the São Francisco Mine and São Vicente Mine (the "Brazilian Mines") in Mato Grosso State, Brazil.

As was indicated in the Company's Annual Information Form dated March 30, 2011, as well as the technical reports dated March 30, 2011 in respect of each of the Brazilian Mines1,2, studies have shown that the reconciliation between the mineral resource models and mine production required further investigation as the Brazilian Mines produced more ore tonnes at lower grades than was predicted by the mineral resource models. As a result, Rogerio Moreno, AusIMM, of MCB Serviços e Mineração Ltda. ("MCB"), the independent Qualified Person for the above-mentioned technical reports, recommended that the mineral resource models be updated and the estimation parameters modified to improve the reconciliation.

1 National Instrument 43-101 compliant technical report dated March 30, 2011, and entitled "Resources and Reserves on the São Francisco Mine in the Municipality of Vila Bela da Santissima Trindade, State of Mato Grosso, Brazil" prepared for Aura Minerals by Rogerio Moreno, AusIMM, of MCB Serviços e Mineração Ltda. (the "São Francisco Technical Report"), a copy of which may be found on SEDAR at www.sedar.com.

2 National Instrument 43-101 compliant technical report dated March 30, 2011, and entitled "Resources and Reserves on the São Vicente Mine in the Municipality of Nova Lacerda, State of Mato Grosso, Brazil" prepared for Aura Minerals by Rogerio Moreno, AusIMM, of MCB Serviços e Mineração Ltda. (the "São Vicente Technical Report"), a copy of which may be found on SEDAR at www.sedar.com.

In updating the mineral resource and reserve estimates for each of the Brazilian Mines, the Company has reinterpreted the geological models used to estimate the mineral resources and reserves. This has resulted in new geological block models that are more tightly constrained to current drilling data and better reflect the discontinuous nature of the mineralization at each mine. Through this process, the Company has developed a new mine plan for each Brazilian Mine to improve reconciliation and confidence in the mine plan production forecasts. However, the reinterpretation of the geological models and the use of updated mine design parameters, including higher cut-off grades reflecting current operating experience, have resulted in a reduction in the mineral resource and reserve estimates at the Brazilian Mines.

The Company has informed the Departamento Nacional de Produção Mineral in Brazil (the Ministry of Mines department responsible for the management of mineral resources) of the changes to the mineral resource and reserve estimates and will be seeking approval of the new mine plans, where required.

Updated Resource and Reserve Estimate at the São Vicente Mine

As stated above, the reinterpretation of the geological model and the use of updated mine design parameters, including a higher mineral resource and reserve cut-off grade of 0.25 g/t gold for dump leach ore ("DLO") and 0.40 g/t gold for crushed gravity ore ("CGO"), have resulted in a reduction in the mineral resource and reserve estimates at the São Vicente Mine.

Table 1 below presents the updated mineral resource estimate for the São Vicente Mine at a 0.25 g/t gold cut-off for DLO and 0.40 g/t gold cut-off for CGO as compared to the December 31, 2010 resource estimate3 at a 0.13 g/t gold cut-off. Table 2 presents the updated mineral reserve estimate at a 0.25 g/t gold cut-off for DLO and 0.40 g/t gold for CGO as compared to the December 31, 2010 reserve estimate4 at a 0.15 g/t gold cut-off.

3 The December 31, 2010 resource estimate is set out in the São Vicente Technical Report.

4 The December 31, 2010 reserve estimate is set out in the São Vicente Technical Report.

The increase in the cut-off grade for mineral resources and reserves to 0.25 g/t gold is primarily based on the following two factors: (i) a significant increase in total operating costs since December 31, 2010, including increased labour costs, contractor rates and costs of consumables and the stronger Brazilian real and inflation; and, (ii) a reduction in DLO recovery based on recent column test work. It is important to note that recovery from DLO only represents a small portion of total gold production from the São Vicente Mine, as the majority of gold production comes from the processing of CGO, the recovery of which remains at 80%.

Table 1 – São Vicente Mine Mineral Resource Estimate

December 31, 20101 September 30, 20112
Mineral Resource Category Tonnes
(000)
Grade
(g/t Au)
Gold Ounces
(000)
Tonnes
(000)
Grade
(g/t Au)
Gold Ounces
(000)
Measured 9,377 0.70 210 4,233 0.95 129
Indicated 5,481 0.67 117 1,737 0.84 47
Total Measured and Indicated Mineral Resources 14,859 0.69 328 5,970 0.91 175
Inferred Resources 1,059 1.02 35 291 0.46 4
Note 1 – 0.13 g/t Cut-off Note 2 – 0.25 g/t (DLO) and 0.40 g/t (CGO) Cut-off

Note: Mineral resources in Table 1 above are inclusive of mineral reserves.

Table 2 – São Vicente Mine Mineral Reserve Estimate

December 31, 20101 September 30, 20112
Mineral Reserve Category Tonnes
(000)
Grade
(g/t Au)
Gold Ounces
(000)
Tonnes
(000)
Grade
(g/t Au)
Gold Ounces
(000)
Proven 7,723 0.73 182 2,165 0.85 59
Probable 3,532 0.62 71 779 0.79 20
Total Proven and Probable Mineral Reserves 11,255 0.70 253 2,943 0.84 79
Note 1 – 0.15 g/t Cut-off Note 2 – 0.25 g/t (DLO) and 0.40 g/t (CGO) Cut-off

Update Resource and Reserve Estimate at the São Francisco Mine

As stated above, the reinterpretation of the geological model and the use of updated mine design parameters, including a higher mineral resource cut-off grade of 0.23 g/t gold, have resulted in a reduction in the mineral resource and reserve estimates at the São Francisco Mine.

Table 3 below presents the updated mineral resource estimate for the São Francisco Mine at a 0.23 g/t gold cut-off as compared to the December 31, 2010 resource estimate5 at a 0.15 g/t gold cut-off. Table 4 presents the updated mineral reserve estimate at a 0.25 g/t gold cut-off as compared to the December 31, 2010 reserve estimate6 at a 0.30 g/t gold cut-off.

5 The December 31, 2010 resource estimate is set out in the São Francisco Technical Report.

6 The December 31, 2010 reserve estimate is set out in the São Francisco Technical Report.

The increase in the cut-off grade for mineral resources to 0.23 g/t gold is based on a determination that material between 0.15 g/t gold and 0.23 g/t gold no longer has a reasonable prospect of economic extraction based on current operating parameters.

It should be noted that the mineral resource tonnages are only marginally larger than the mineral reserve tonnages despite applying a higher gold price of $1,700 per ounce for the mineral resource pit shell versus $1,500 per ounce for mineral reserves. This is due to a larger practical pit design used to bring in maximum ounces and provide operational flexibility.

Table 3 – São Francisco Mine Mineral Resource Estimate

December 31, 20101 September 30, 20112
Mineral Resource Category Tonnes
(000)
Grade
(g/t Au)
Gold Ounces
(000)
Tonnes (000) Grade
(g/t Au)
Gold Ounces
(000)
Measured - - - - - -
Indicated 21,631 1.01 706 10,923 0.95 334
Total Indicated Mineral Resources 21,631 1.01 706 10,923 0.95 334
Inferred Resources 62 3.05 6 83 0.47 1
Note 1 – 0.15 g/t Cut-off Note 2 – 0.23 g/t Cut-off

Note: Mineral resources in Table 3 above are inclusive of mineral reserves.

Table 4 – São Francisco Mine Mineral Reserve Estimate

December 31, 20101 September 30, 20112
Mineral Reserve Category Tonnes
(000)
Grade
(g/t Au)
Gold Ounces
(000)
Tonnes
(000)
Grade
(g/t Au)
Gold Ounces
(000)
Proven - - - - - -
Probable 13,731 1.29 569 10,890 0.91 318
Total Probable Mineral Reserves 13,731 1.29 569 10,890 0.91 318
Note 1 – 0.30 g/t Cut-off Note 2 – 0.25 g/t Cut-off

Key Aspects of the Proposed New Mine Plan for the São Vicente Mine:

  • Reduced mine life from 2014 to mid-2013, with leaching operations expected to continue through to the end of 2013;
  • Reduced waste tonnes mined from 33.9 million tonnes in the current three-year mine plan to approximately 5.0 million tonnes over 2012-2013, or by approximately 85%, and a reduction in the strip ratio from approximately 4.3 : 1 to 1.5 : 1;
  • Total gold recovery in 2012-2013 under new mine plan expected to produce 55,000 to 60,000 ounces; and
  • The reduced mining and haulage costs associated with considerably less waste and the elimination of two rainy seasons, which have historically resulted in low production and high cost quarters, are expected to result in cash costs7 of between $1,200 - $1,300 per ounce for 2012.

Key Aspects of the Proposed New Mine Plan for the São Francisco Mine:

  • Reduced mine life from 2015 to second half of 2014, with leaching operations expected to continue into 2015;
  • Life of mine strip ratio of approximately 2.8 : 1, a reduction from the current life of mine strip ratio of approximately 3.7 : 1;
  • Total gold recovery from 2012-2014 under new mine plan expected to be approximately 236,000 ounces, and;
  • The mining and processing of lower grade ore material during the first half of 2012 is expected to result in increased cash costs7 to above $1,500 per ounce. However, cash costs7 are expected to decrease to less than $1,200 per ounce in the second half of 2012 and further decrease to under $1,000 per ounce in 2013 and 2014 as progressively higher grade ore is mined as the pit deepens.

Results of the Proposed New Mine Plans

The shortened mine lives and the decrease in mineral reserves and resources have resulted in the Company assessing whether the carrying value of the Brazilian Mines' long-lived assets and related goodwill are impaired. The Company is currently finalizing this assessment and expects to record an impairment charge of approximately $40 million in its third quarter 2011 results, based on consensus gold price forecasts and the positive implementation of new Brazilian tax laws with respect to PIS/COFINS, among other assumptions.

Commenting on the new mine plans, Mr. Jim Bannantine, President and CEO of Aura Minerals, stated, "The new mine plans resulting from our re-interpretation of the resource models have produced mixed results. While we are disappointed that the reduced mine lives and the lower grades at the São Francisco Mine will reduce total recoverable ounces, the new optimized pits have been designed to lower cash costs7 and decrease operational risk at these operations. We also continue to look at other opportunities to optimize efficiencies and increase gold production from these mines. At the São Vicente Mine, for example, we continue to find small quantities of ore that were considered waste in the resource model, and this continues to benefit production at this operation. The $12 million slimes retreatment plant for recovery of gold in the tailing slimes at the São Francisco Mine is no longer being considered. Rather, the slimes will be applied directly on the leach pads and, with little additional cost, are expected to generate an additional 4,000 ounces of gold annually. Lastly, it should also be noted that we have amended our credit facilities to allow for gold hedging and, given the current level of gold prices, we anticipate implementing a gold hedge program, either in the form of collars or forwards to take advantage of the higher prices and secure cash flows at these operations."

7 See cautionary note regarding non-GAAP measures.

Mineral Resource and Reserve Estimation Procedures for the Brazilian Mines

The resource and reserve estimation for the Brazilian Mines has been prepared for Aura Minerals, under the direction of Ivan C. Machado, M.Sc., P.E., P.Eng., Principal of TechnoMine Services, LLC, an independent Qualified Person for the purpose of National Instrument 43-101. A report under National Instrument 43-101, disclosing the updated resource and reserve estimates for each of the Brazilian Mines, is being prepared by MCB, under the direction of Mr. Machado and will be filed by Aura Minerals on SEDAR within 45 days. Mr. Machado has also reviewed and approved the contents of this news release as applicable.

The mineral resources and reserves for the São Vicente Mine were estimated by using ordinary kriging constrained by five 3D mineralization solids. These solids were defined via structural knowledge and a combination of quartz veining, sericite alteration, and approximately a 0.30 ppm gold cut-off. Block dimensions were 10 x 10 x 10 m. The deposit has been tested by 61,157 m of drilling, comprised of 396 surface and underground holes drilled between 1990 and January, 2011. Grade estimation was based on analyses of 13,069 (12,713 valid and 356 missing/not sampled) five-metre fixed-length composites. Statistical analysis identified high-grade outliers and a total of 39 gold composites were capped within the mineralized zones, with a further six composites capped outside those zones. The average metal loss across the entire deposit was approximately 11%; however, gold metal content within the Main Zone was reduced by only 4.7%.

The mineral resources and reserves for the São Francisco Mine were estimated by using ordinary kriging constrained by three 3D solids that were defined by alteration, sulphide content, the presence of visible gold and interval gold grade. An indicator block model was used to further divide these zones into higher and lower grade domains based on the probability of a block having a grade greater than a 0.15 ppm gold cut-off; which was found to best model the potentially economic mineralization. Block dimensions were 10 x 10 x 10 m. The deposit has been tested by 93,667 m of drilling, comprised of 524 core holes drilled between 1990 and November, 2010. Grade estimation was based on analyses of 19,492 five-metre fixed-length composites. Statistical analysis identified high-grade outliers and a total of 20 gold composites were capped within the high grade domains, representing an average metal loss within this zone of 5.8%. Within the low grade domains, 101 composites were capped, representing an average metal loss of 15%. An additional nine composites were capped within the waste.

Non-GAAP Measures

This news release includes a non-GAAP performance measures, in particular, the total cash costs of gold per ounce produced. This non-GAAP measure does not have any standardized meaning within International Financial Reporting Standards ("IFRS") and therefore may not be comparable to similar measures presented by other companies. The Company believes that this information is useful to management and certain investors in evaluating the Company's performance. The data presented is intended to provide additional information and should not be considered in isolation or as a substitute for measures of performance prepared in accordance with IFRS. Cash costs are presented as they represent an industry standard method of comparing certain costs on a per unit basis. Total cash costs include on-site mining, processing and, administration costs, off-site refining and royalty charges, reduced by by-product credits, but exclude amortization, reclamation, and exploration costs, as well as capital expenditures. Total cash costs are divided by ounces produced to arrive at per ounce cash costs.

About Aura Minerals Inc.

Aura Minerals is a Canadian mid-tier gold and copper production company focused on the exploration, development and operation of gold and base metal projects in the Americas. The Company's producing assets include the San Andres gold mine in Honduras, the São Francisco and São Vicente gold mines in Brazil and the copper-gold-silver Aranzazu Mine in Mexico. Other significant assets include the feasibility-stage Serrote Deposit at the copper-gold-iron ore Arapiraca Project in Brazil.

For further information, please visit Aura Minerals' web site at www.auraminerals.com.

Cautionary Statement

This document contains "forward-looking information" within the meaning of Canadian securities legislation and "forward-looking statements" within the meaning of the United States Private Securities Litigation Reform Act of 1995. This information and these statements, referred to herein as "forward-looking statements" are made as of the date of this news release or as of the effective date of information described in this news release, as applicable. Forward-looking statements relate to future events or future performance and reflect current estimates, predictions, expectations or beliefs regarding future events and include, without limitation, statements with respect to: (i) the amount of mineral reserves and mineral resources; (ii) the amount of future production over any period; (iii) the amount of waste tonnes mined; (iv) the amount of mining and haulage costs; (v) cash costs; (vi) operating costs; (vii) strip ratios and mining rates; (viii) expected grades and ounces of metals and minerals; (ix) expected processing recoveries; (x) expected time frames; (xi) prices of metals and minerals; (xii) mine life; and (xiii) anticipated gold hedge programs. Any statements that express or involve discussions with respect to predictions, expectations, beliefs, plans, projections, objectives, assumptions or future events or performance (often, but not always, using words or phrases such as "expects", "anticipates", "plans", "projects", "estimates", "envisages", "assumes", "intends", "strategy", "goals", "objectives" or variations thereof or stating that certain actions, events or results "may", "could", "would", "might" or "will" be taken, occur or be achieved, or the negative of any of these terms and similar expressions) are not statements of historical fact and may be forward-looking statements.

All forward-looking statements are based on the Company's or its consultants' current beliefs as well as various assumptions made by and information currently available to them. These assumptions include, without limitation: (i) the presence of and continuity of metals at the Brazilian Mines at modeled grades; (ii) the capacities of various machinery and equipment; (iii) the availability of personnel, machinery and equipment at estimated prices; (iv) exchange rates; (v) metals and minerals sales prices; (vi) appropriate discount rates; (vii) tax rates and royalty rates applicable to the mining operations; (viii) cash costs; (ix) anticipated mining losses and dilution; (x) metals recovery rates, (xi) reasonable contingency requirements; and (xiii) receipt of regulatory approvals on acceptable terms. Although management considers these assumptions to be reasonable based on information currently available to it, they may prove to be incorrect. Many forward-looking statements are made assuming the correctness of other forward looking statements, such as statements of net present value and internal rate of return, which are based on most of the other forward-looking statements and assumptions herein. The cost information is also prepared using current values, but the time for incurring the costs will be in the future and it is assumed costs will remain stable over the relevant period.

By their very nature, forward-looking statements involve inherent risks and uncertainties, both general and specific, and risks exist that estimates, forecasts, projections and other forward-looking statements will not be achieved or that assumptions do not reflect future experience. We caution readers not to place undue reliance on these forward-looking statements as a number of important factors could cause the actual outcomes to differ materially from the beliefs, plans, objectives, expectations, anticipations, estimates assumptions and intentions expressed in such forward-looking statements. These risk factors may be generally stated as the risk that the assumptions and estimates expressed above do not occur, but specifically include, without limitation, risks relating to variations in the mineral content within the material identified as mineral reserves and mineral resources from that predicted, changes in development or mining plans due to changes in logistical, technical or other factors, the impact of general business and economic conditions, global liquidity and credit availability on the timing of cash flows and the values of assets and liabilities based on projected future conditions, fluctuating metal prices (such as gold, copper, silver, nickel and iron ore), currency exchange rates (such as the Canadian dollar, Brazilian Real, Mexican Peso and the Honduran Lempira versus the United States dollar), possible variations in ore grade or recovery rates, changes in accounting policies, changes in the Company's corporate resources, changes in project parameters as plans continue to be refined, changes in project development and production time frames, the possibility of project cost overruns or unanticipated costs and expenses, higher prices for fuel, steel, power, labour and other consumables contributing to higher costs and general risks of the mining industry, failure of plant, equipment or processes to operate as anticipated, unexpected changes in mine life, final pricing for concentrate sales, unanticipated results of future studies, seasonality and unanticipated weather changes, costs and timing of the development of new deposits, success of exploration activities, successful completion of proposed acquisitions, permitting time lines, government regulation of mining operations, environmental risks, unanticipated reclamation expenses, title disputes or claims, limitations on insurance coverage and timing and possible outcome of pending litigation and labour disputes, as well as those risk factors discussed or referred to in the Company's Annual Information Form, dated March 30, 2011, under the heading "Item 4.2 – Risk Factors", in the annual financial statements and management's discussion and analysis of the Company for the year ended December 31, 2010, in the São Francisco Technical Report, in the São Vicente Technical Report and in the technical reports relating to each of the Brazilian Mines expected to be filed by the Company within 45 days. The foregoing list of factors that may affect future results is not exhaustive.

When relying on our forward-looking statements, investors and others should carefully consider the foregoing factors and other uncertainties and potential events. The Company does not undertake to update any forward-looking statement, whether written or oral, that may be made from time to time by the Company or on behalf of the Company, except as required by law.

The forward-looking statements contained herein is presented for the purpose of assisting investors in understanding the Company's expected financial and operational performance and results as at and for the periods ended on the dates presented in the Company's plans and objectives and may not be appropriate for other purposes. The reader is also cautioned that mineral resources that are not mineral reserves do not have demonstrated economic viability.

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