Sierra Metals Files 43-101 Technical Report Reflecting an 86% Increase in Resources at the Yaricocha Mine in Peru

VANCOUVER, May 12, 2015 /PRNewswire/ - Sierra Metals Inc. (TSX: SMT) (BVL: SMT) ("Sierra Metals" or the "Company") has filed a National Instrument 43-101 ("NI 43-101") technical report in support of the press release issued on March 31, 2015 announcing an 86% increase over the previously reported mineral resource for the Yauricocha Mine in Peru.

The independent technical report, entitled "NI 43-101 Technical Report on the Yuaricocha Mine" (the "Technical Report"), effective date December 31, 2014, was prepared for Sierra Metals by Gustavson Associates. The Technical Report is available under the Company's profile on SEDAR at www.sedar.com and on the Company's website at www.sierrametals.com. 

The below is a repeat of the March 31, 2015 press release for the benefit of shareholders.

Highlights

• Total Proven and Probable Mineral Reserves for Yauricocha are 5,377,000 tonnes averaging 75.5 g/t silver, 1.41% lead, 0.80% copper, 2.34% zinc and 0.92 g/t gold; down from 6,394,000 tonnes at October 1, 2013.
• Total Measured and Indicated Mineral Resources for Yauricocha, inclusive of the Mineral Reserves, are 11,411,000 tonnes averaging 55.4 g/t silver, 0.85% lead, 0.83% copper, 1.73% zinc and 0.76 g/t gold; up from 6,139,000 tonnes at October 1, 2013.
• The 16% reduction in reserve tonnage is due to several factors including the change in modelling methodology, the exclusion of 350,000 tonnes from Victoria and Ipillo Mines, the application of the current metal price and concentrate sales environments, and the elevated depletion of relatively higher grade reserves from the Mascota ore body since October 1, 2013. 
• The 86% increase in resource tonnage is predominantly in the Indicated category of polymetallic mineralization and is the result of the successful exploration programs that have extended ore bodies at depth in the Central Mine area.
• The updated silver equivalent grade ("AgEq") for the Proven and Probable Reserves is 338.6 g/t.  Although this cannot be directly compared with the previous AgEq estimate of 360.6 g/t, the reduction is indicative of the change to the current reserves based upon the existing metal prices and concentrate sales terms.

Mineral Resource Estimate

The effective date of this resource estimate is December 31, 2014 and was completed by Gustavson Associates, LLC.  Thomas Matthews, MMSA QP, Principal Resource Geologist with Gustavson, is the Qualified Person responsible for this resource estimate.  Gustavson Associates validated the database used for resource estimation, created domain wireframes corresponding to the main mineralized zones, interpolated grade into block models within these mineralized bodies, and reviewed the mine-mill reconciliation results.  Gustavson considers the resource to meet industry standard practices, and to be CIM and NI 43-101 compliant.

For all mineralization types, resources are presented at a cut-off which corresponds to the value of recoverable metal of $37 per tonne; this value being the approximate value of direct mining and processing costs at Yauricocha.  Metal prices used in this determination were $18.10/oz silver, $0.95/lb lead, $3.02/lb copper, $0.91/lb zinc and $1,241/oz gold.  Metal recovery was set at historical performance for each mineralization type.

Resource Estimate Effective Date December 31, 2014

Table 1: Measured Resources

Table 2: Indicated Resources

Table 3: Measured and Indicated Resources

Table 4: Inferred Resources

The mineral reserves are included within these mineral resources.  Quality and grade are estimates and are rounded to reflect the fact that the resource estimate is an approximation. Mineral resources are not mineral reserves and do not demonstrate economic viability.  There is no certainty that all or any part of the mineral resource will be converted to mineral reserves.  Quantities may not sum due to rounding.

Silver Equivalency is represented as a recovery-adjusted value for silver, lead, copper, and zinc, represented as silver-equivalent grade according to the formula:

AgEq =

Ag + (Pb*Ppb*Rpb*22.05)+(Cu*Pcu*Rcu*22.05)+(Zn*Pzn*Rzn*22.05)+(Au*Pau*Rau/31.1035) (Pag* Rag/31.1035)

Where the symbols represent:

Table 5:  Silver Equivalent Calculation Values

Metals price assumptions are based on 6-month trailing averages as of the effective date of the resource estimation.  Six month averages were used as a proxy for spot prices, because the 3-year averages which Gustavson typically employs are significantly higher and might overstate the resource and economics.  Recovery assumptions are based on 2-year trailing average production recoveries for the Chumpe plant.

The reader is advised that the silver equivalency stated here is based upon updated price and recovery factors; therefore a direct comparison with previous resource and reserve estimates should not be made.

Mineral Reserve Estimate

The effective date of this reserves estimate is December 31, 2014.  The mineral reserve was estimated by applying modifying factors to the mineral resources.  Yauricocha is an operating mine, with significant production history.  Because of this, the primary basis for the modifying factors applied for reserves definition is actual historic cost, recovery, and mine planning data.  Gustavson considers the reserves to meet industry standard practices, and to be CIM and NI 43-101 compliant.

Mineral reserves are defined as that portion of mineral resources which are economically extractable, and for which there is mining access planned.   The stated reserves include factors for dilution, ore loss, and mine-mill reconciliation.  Therefore the grades are somewhat less than the resources, and the tonnages are somewhat higher.  Reserves are presented at a NSR cut-off based on value of recoverable metal, less an allowance for refining costs.  Cutoffs vary by zone, include all operating costs and G&A, and reflect mining cost assumptions for each zone. Cutoffs vary from $42 to $87 per tonne depending on mining method. However due to bulk mining methods employed, some marginal value blocks inside of stope shapes are included as reserves.

Reserve Estimate Effective Date December 31, 2014

Table 6: Yauricocha Proven Mineral Reserves

Table 7: Yauricocha Probable Mineral Reserves

Table 8: Yauricocha Proven and Probable Mineral Reserves

Quality and grade are estimates and are rounded to reflect the fact that the reserve estimate is an approximation. Quantities may not sum due to rounding.

Quality Control

The quality assurance-quality control (QA-QC) program employed by Sierra Metals has been reviewed by Gustavson.  Gustavson considers that the QA-QC program meets industry standards, and to be CIM and NI 43-101 compliant.

Qualfied Persons

The mineral resource and reserve estimate was prepared by Thomas Matthews, MMSA QP, Principal Resource Geologist with Gustavson Associates, LLC. Mr. Matthews  is a qualified person as defined by NI 43-101 and has reviewed and approved the contents of this press release with respect to the mineral resource and reserve estimate at the Yauricocha Mine.

About Sierra Metals

Sierra Metals Inc. is a Canadian mining company focused on the production of precious and base metals from its Yauricocha Mine in Peru, and its Bolivar Mine and Cusi Mine in Mexico. In addition, Sierra Metals is exploring 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, and the San Miguelito gold properties in Northern Peru. Projects in Mexico include Bacerac (silver) in the state of Sonora and La Verde (gold) at the Batopilas Property in the state of Chihuahua.

The Company's shares trade on the Lima Stock Exchange (Bolsa de Valores de Lima) and the Toronto Stock Exchange under the symbol "SMT".

Cautionary Statement Regarding Forward-Looking Information

Except for statements of historical fact, the statements in this press release contain certain "forward-looking information" within the meaning of Canadian securities laws. Forwardlooking information is frequently characterized by words such as "plan", "expect", "project", "intend", "believe", "anticipate", "estimate" and other similar words, or statements that certain events or conditions "may" or "will" occur. Forward-looking statements include, but are not limited to, statements regarding the Company's estimation of mineral reserves and resources and the realization of mineral reserve estimates (including all assumptions), the prospectivity of the Yauricocha Project, the ability to identify new resources and convert resources and exploration potential into reserves, the timing, nature and success of exploration activities. Forwardlooking statements are based on the opinions and estimates of management at the date the statements are made, and are subject to a variety of risks and uncertainties and other factors that could cause actual events or results to differ materially from those anticipated in the forwardlooking statements, including, among others, the accuracy of mineral grades and related assumptions, inherent operating risks, planned expenditures, proposed exploration and development at the Yaurichocha Project, operating and economic aspects of the Yaurichocha Project, as well as those risk factors identified in the Company's Annual Information Form filed under the Company's SEDAR profile. Such statements are based on a number of assumptions which may prove to be incorrect, including assumptions about: business and economic conditions; commodity prices and the price of key inputs such as labour, fuel and electricity; credit market conditions and conditions in financial markets generally; revenue and cash flow estimates, production levels, development schedules and the associated costs; ability to procure equipment and supplies and on a timely basis; the timing of the receipt of permits and other approvals for projects and operations; the ability to attract and retain skilled employees and contractors for the operations; the accuracy of reserve and resource estimates; the impact of changes in currency exchange rates on costs and results; interest rates; taxation; and ongoing relations with employees and business partners. Should one or more of the foregoing risks and uncertainties materialize, or should underlying assumptions prove incorrect, actual results may vary materially from those described in the 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.

Cautionary Note to U.S. Investors Concerning Measured, Indicated and Inferred ResourcesThis press release uses the terms "measured," "indicated" and "inferred" resources. We advise investors that while those terms are recognized and required by Canadian regulations, the United States Securities and Exchange Commission does not recognize them. "Inferred" resources" have a great amount of uncertainty as to their existence and as to their economic and legal feasibility. It cannot be assumed that all or any part of an inferred resource will ever be upgraded to a higher category. Under Canadian rules, estimates of inferred mineral resources may not form the basis of feasibility or other economic studies. United States investors are cautioned not to assume that all or any part of measured or indicated mineral resources will ever be converted into mineral reserves. United States investors are also cautioned not to assume that all or any part of an inferred mineral resource exists, or is economically or legally mineable.

SOURCE Sierra Metals Inc.