Toronto, Ontario – April 17, 2013 – Sierra Metals Inc. (TSX-V:SMT) (BVL:SMT) (“Sierra Metals” or the “Company”; previously Dia Bras Exploration) is pleased to announce that a pre-feasibility study has been completed by Gustavson Associates, LLC of Lakewood, Colorado, for its Bolivar copper-zinc-silver mine located in Chihuahua State, Mexico.  The study, mine plan and reserve estimate are based on Gustavson’s work and mine plan on a lower-grade portion of the resources, mainly at its El Gallo Inferior deposit.   The evaluation of the higher grade portions of the mine still require further technical studies, which should result in additional resources and continued feed of ore to its processing plant and potentially lead to future reserve additions over the next 10 months.

Press Release Highlights:

  • Bolivar now has Proven and Probable ore reserves totalling 7,456,806 tonnes at 1.044% Cu-Equivalent averaging 19.5 g/t silver, 0.759% Cu, 0.329% Zn.  Gold contents average 0.226 g/t but were not included in the CuEq calculation, but were included within the project’s economics.

  • These reserves are in the Gallo Inferior deposit, which is the lower-grade portion of resources defined in the October 15, 2012 NI 43-101 Technical Report.  The October 2012 report defined 15,404,000 tonnes of Measured and Indicated Resources averaging 19.4 g/t silver, 0.79% copper, and 1.01% zinc at a cut-off grade of 0.66% CuEq.  Gold contents averaged 0.226 g/t and were added to the Resource model in January 2013 using the same data used to do the NI 43-101 Technical Report.

  • Out of the 15.4 million tonnes of Measured and Indicated Resources, 6.1 million tonnes of the highest grades deposits (i.e. Alta Ley and portions of Gallo Superior deposits) were not included at this stage in the reserve calculation because more data are required for mine planning purposes.  Additional drilling is underway to complete mine planning in order to convert these Measured and Indicated resources to Proven and Probable Reserves.

  • Of the modelled tonnage of 9 million tonnes of the lower grade Measured and Indicated Resources, approximately 80% were converted to ore reserves.

  • At a production rate of 2,000 tonnes per day, these reserves provide a 10-year mine life with an additional year of processing from the stockpile for a total of 11 years.

  • Bolivar is currently in commercial production at an ore throughput rate of 1,000 tons per day and should double its production capacity to 2,000 tons per day by the end of May 2013.

Daniel Tellechea, President and CEO of Sierra Metals, commented: “Sierra Metals advances another major step in the Company’s evolution with the completion of this pre-feasibility study that defines for the first time in the history of the Bolivar mine a formal proven and probable reserve.  Not only does Bolivar have reserves now for the next 10 years at its expanded 2,000 ton per day mill, but we are conducting additional significant drilling in two areas to add to its mine life.  First, we are drilling those portions of the Gallo Superior and Alta Ley that did not have sufficient density of drilling for mine planning purposes to generate a reserve.  It is important to note that the Gallo Superior and Alta Ley measured and indicated resources are higher grade than Gallo Inferior.  Second, we are focusing our exploration drilling in target areas that have been defined by geophysics and fault extensions from the Alta Ley mine in order to increase resources and grade.  These faults controlled high-grade copper-zinc mineralization in the Superior portion of the Alta Ley area, and during 2005-2011 we processed 681,305 tonnes averaging 1.65% copper and 8.47% zinc.  Our new targets are mineralized zones of similar grade.”

Sierra Metals has conducted exploration, development and mining at the Bolívar Mine since 2004.  Exploration includes geologic mapping and diamond core drilling in the El Gallo, Increíble and Alta Ley areas, which are located within the area of resource modeling, and in the La Narizona, La Montura, La Pequeña and El Val areas, which are located outside the area of resource modeling.  Pilot mining has been conducted and has provided valuable information regarding metallurgy, recovery rates, smelter treatment and refining charges, etc.

Bolivar built its new Piedras Verdes ore processing mill in 2010-2011 and declared commercial production in November 2011 with a processing capacity of 1,000 tonnes per day.  The data of prior production were used in the development of the pre-feasibility study preparation and as a guide to continued mining as well as doubling of production capacity to 2,000 tons per day, which will be effective by the end of May 2013.

This work resulted in a NI 43-101 and CIM compliant resource estimate (see press release of August 30, 2012), which is the basis for this pre-feasibility study.  Table 1 shows the Measured and Indicated Resources of the compliant resource estimate.

Table 1: Deposit M+I with  Tonnes and Grade



Ag (gpt)

Cu (%)

Zn (%)

CuEq (%)

Au (gpt)

El Gallo Superior







El Gallo Inferior









Not Modeled

Alta Ley






Not Modeled








Note:  CuEq>0.66 AND M&I  

Gustavson received diamond drill data for 683 drill holes located within the area of the underground mine workings, and in the Bolívar III, Bolívar IV, and Piedras Verdes concessions to characterize the skarn-type mineralization.  Data from these holes as well as underground mapping and sampling were included in the study.

The recovered tonnes, including dilution, for each area were then scheduled for production.  The total tonnes and grades shown in Table 2 constitute the Reserve Statement for the Bolivar Project as of the date of this pre-feasibility report.  These tonnes are from only portions of the El Gallo Superior and El Gallo Inferior.  Additional information, namely additional drill holes, is required to upgrade the Measured and Indicated tonnes at Alta Ley plus un-mined areas of Gallo Superior to reserves.

On an overall recovery of the Gallo Deposits, 7.46 million tonnes are mined from the Gallo Superior and Inferior deposits (2.04 + 8.55 million tonnes for a total of 10.59 million tonnes). This is an overall recovery of 70.5% of the material modeled.  However, from the economic model where only the final logical mine layout was used, the recoveries of the mineable Resources range from 76.0 % to 83.5%. Essentially the mine plan recovers 70.5% of the M+I, but recovers 76-83% of the mineable M+I.

This Reserves Statement has an effective date of December 31, 2012 and was completed by Gustavson as an independent report under the supervision of Karl D. Gurr, Qualified Person as defined by NI 43-101.

Table 2  Combined Reserve Statement for the Bolivar Project

RoM Tonnes + Diluted Grades


Ag gpt

Cu %

Zn %

CuEq % (no Au)

Au gpt








RoM – Measured – Proven







RoM – Indicated – Probable







Waste – Inferred







Total P+P







Total P+P+Waste







RoM = Run of mine

Gustavson believes that these deposits may have additional potential as data collection and interpretation continue, but this reserve statement provides a snapshot at this point in time.  Continued exploration success at the mine may justify further production expansion in the future.

Quality Assurance

The technical content of this news release has been approved by Thomas L. Robyn, Ph.D., CPG, RPG, a Qualified Person as defined in NI 43-101 and Senior Vice President, Exploration, for Sierra Metals, Inc.

About Sierra Metals

Sierra Metals Inc. is a Canadian mining company focused on precious and base metals from its Yauricocha mine in Peru and its Bolivar mine in Mexico. The Company is also advancing its Cusi silver project in Mexico from advanced development into commercial production. In addition, Sierra Metals is xploring several precious and base metal targets in Peru and Mexico. Projects in Peru include Adrico (gold), Victoria (copper-silver) and Ipillo (polymetallic) at the Yauricocha Property in the province of Yauyos. Projects in Mexico include Bacerac (silver) in the state of Sonora, La Verde (gold) at the Batopilas Property in the state of Chihuahua, and Las Coloradas (silver) at the Melchor Ocampo Property in the state of Zacatecas.

The Company’s shares trade on the Bolsa de Valores de Lima and TSXV under the symbol “SMT”.

For further information on Sierra Metals, please visit www.sierrametals.com or contact:


Daniel Tellechea
President & CEO
Sierra Metals Inc.
1 (866) 493

Matt Morrish
Director, Investor Relations
Sierra Metals Inc.
1 (866) 493

This press release does not constitute an offer to sell or solicitation of an offer to buy the securities in the United States or any other jurisdiction. The Common Shares will not be and have not been registered under the United States Securities Act of 1933, as amended, and may not be offered or sold in the United States absent registration or an applicable exemption from the registration requirements.

Neither the TSXV nor its Regulation Services Provider (as that term is defined in policies of the TSXV) accepts responsibility for the adequacy or accuracy of this release.

Forward-Looking Statements

Except for statements of historical fact contained herein, the information in this press release may constitute “forward-looking information” within the meaning of Canadian securities law. Other than statements of historical fact, all statements are “forward-looking statements”, which involve various known and unknown risk and uncertainties and other factors, including market conditions that may affect the Company’s ability to execute its current business plan.  Actual results might differ materially from results suggested in any forward-looking statements. The Company assumes no obligation to update the forward-looking statements, or to update the reasons why actual results could differ from those reflected in the forward-looking statements unless and until required by securities laws applicable to the Company. Additional information identifying risks and uncertainties is contained in filings by the Company with the Canadian securities regulators, which filings are available at www.sedar.com.



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