Mirasol Reports Coeur's Updated Resource Estimate for the Joaquin Project with 39.7 Million Measured + Indicated, plus 31.7 million Inferred Silver Ounces Accessible by Open Pit

VANCOUVER, Aug. 7, 2012 /CNW/ - Mirasol Resources Ltd. (TSX-V: MRZ, Frankfurt: M8R) is pleased to announce the second National Instrument 43-101 resource estimate for the Joaquin Silver-Gold Project, Santa Cruz Province, Argentina, as prepared by an independent consultant for Mirasol's joint venture partner, Coeur d'Alene Mines ("Coeur").  The estimate is an in-pit resource for the La Negra and La Morocha deposits, and includes 39.7 million ounces of silver in the measured and indicated categories, and 31.7 million ounces of silver in the inferred category, when both oxide and sulphide mineralization are combined for the two adjacent deposits (Table 1, Figure 1 ).

Table 1. Resources Joaquin Project Totals

Mineral resources that are not mineral reserves have not demonstrated economic viability

The estimate was prepared according to NI 43-101 standards and in accordance with CIM Standards on Mineral Resources and Reserves: Definitions and Guidelines (CIM 2005) by independent consulting firm NCL Ingenieria y Construcción Ltda. ("NCL") of Chile, which was selected and contracted by Coeur, and who also performed the original NI 43-101 resource estimate (press release May 9, 2011).

Also, a significant amount of infill diamond drill hole data was not incorporated into the current estimate due to time constraints, particularly from the La Morocha deposit.  Mirasol has received assay results from many of the omitted holes, that include the best hole (DDJ-277) containing a 35.3 metre core length intercept of 704 grams per tonne (g/t) silver and 0.24 g/t gold, which includes 15.3 metres of 2,372 g/t silver and 0.90 g/t gold.  The infill holes in the Morocha deposit confirm grade and continuity, and Mirasol expects their eventual inclusion will further increase the confidence classification of the resource, and perhaps also increase the average silver grade. (Table 4 and Appendix 1).

Geological data was used to separate the mineralization into oxide and sulphide types, and discreet mineralized bodies were defined by geology and grade shells to spatially limit the assay data.  At Morocha, a single tabular body, dipping moderately north-easterly, was defined.  At La Negra, a sub-vertical feeder and sub-horizontal manto (planar tabular) bodies were defined.

The in-pit resources have been computer-modeled by Whittle® Pit mine shells designed using the technical parameters determined by Coeur's Technical Services Group and accepted by NCL (Table 2).  They include Coeur's current estimates of the operating costs and parameters.  Sufficient work has not yet been done to classify the resources as reserves and the parameters used in Table 2 are considered to be preliminary in nature.  The resources are not demonstrated to have economic viability at this stage, but are believed to have a reasonable probability of doing so, when required additional engineering studies are completed.

Table 2. Parameters used for Whittle® Pits

Resources reported herein are only those within the pit shell designed using the parameters in Table 2, and only those within the pit shells that exceed the cut-off grade.  Project-specific metallurgical test work is at preliminary stage at Joaquin.  Additional test work has been performed since the initial resource estimate, however it was decided not to change the assumptions of the metallurgical recovery parameters.  It was determined that lower processing costs are to be expected for the oxide mineralization than the sulphide mineralization (Table 2) and this was incorporated into the pit design.  The sulphide mineralization is, however, higher grade on average.  For the purposes of reporting the current resource estimate results, a cut-off grade of 25 g/t silver was used for oxide mineralization, and a cut-off of 37 g/t silver was used from sulphide mineralization for mineralization within the pit design.  Most of the resource is comprised of oxide mineralization (74% of the silver ounces) with lesser sulphide mineralization (26% of the silver ounces).  The majority of the sulphide mineralization is found at La Morocha where it occurs beneath oxide mineralization.

The current resources are tabulated on a project-wide basis (Table 1), as well as separately for the La Morocha (Table 3A) and La Negra (Table 3B) deposits, and are differentiated by category into those resources categorized as Measured and Indicated (with greater confidence levels) and Inferred (lesser confidence level), and by mineralization type into oxide and sulphide types.   Individually, on a tonnage basis, the La Negra resource has progressed from 53% Indicated with no Measured in May 2011 to a current combined 89% Measured and Indicated classification (Figure 2).  At La Morocha in May 2011 there was no Measured and 4% Indicated and this has now progressed to Measured and Indicated of 27%.  On a project-wide basis, 62% of the resource tonnes have now been classified as Measured and Indicated while the remaining 38% are classified as Inferred. This is a large increase over the initial resource estimate (May 2011) in which 34% of the total tonnes were classified as Indicated and the remainder as Inferred.

Table 3A. Resources La Morocha Deposit

Table 3B. Resources La Negra Deposit

Due to time constraints, NCL was unable to include 29 infill holes and 2 metallurgical holes at the Morocha deposit, and 13 infill and expansion holes at the La Negra deposit in the estimate (Figures 3 and 4).  Results of infill drilling at La Morocha have been very successful in confirming the current resource, and infill drilling cut some of the longest intercepts and highest silver grades to date (Figure 3, Tables 3 and 4, and Appendices 1 and 2).  Mirasol expects that incorporation of these unused holes at La Morocha will significantly increase the percentage of tonnes in the Measured and Indicated categories, which currently represent 27% of the total tonnes, to a much higher percentage, as occurred at La Negra where the percentage increased from 53% as Indicated to 89% as Measured and Indicated, when the infill holes were included (Figure 2).

Table 4. Highlights of Drill Intercepts Not Included in the Current Resource Estimate

• Silver equivalent is calculated as AgEQ g/t = Ag g/t + 65 x Au g/t. Metallurgical recoveries are assumed to be 100%.
• Primary intersections are calculated at a cutoff grade of 20 g/t with some internal dilution allowed at the discretion of the project's Qualified Person.
• "Included" intersections are calculated at a 50 g/t or higher cutoff grade.
• Reported grades are not capped.
• Estimated true widths have not been calculated and the AgEq gram metre product is thus based on the uncorrected core lengths of the intercepts
• + indicated holes are considered preliminary pending QA/QC data for certified standards
• ^ the two indicated holes have 5m gaps in sampling which are assumed to have zero grade herein

Currently Mirasol holds a 49% interest in the Joaquin Joint Venture.  Coeur may earn a 61% interest by completing a full feasibility study that meets criteria for bank financing, which is currently underway.  On delivery of the feasibility study, Mirasol may retain a 39% participating interest or, at its election, request that Coeur provide mine financing, and in return Coeur may increase its participation to 71% in the project if it elects to proceed to the next stage.

Mirasol looks forward to future upgrades in the confidence classification of the Joaquin Project resources through incorporation of unused drill data, as well as expansion through the exploration for new deposits on this highly prospective property.  At the present time, results are pending on 34 drill holes (DDJ-284 to 315), most of which were drilled on new exploration targets.  The new resource estimate presented here represents a significant increase in confidence in the geometry, nature and grade of the La Negra and La Morocha silver-gold deposits and thus reduces uncertainty and shareholder risk associated with the resources.  It also represents a significant step towards Coeur's goal of completing a feasibility study which meets bank finance criteria.

NCL and Coeur have provided technical information to Mirasol upon which Mirasol is relying. NCL is currently finalizing a NI 43-101 Technical Report describing in detail the methods and work on the Joaquin Project resource on behalf of Mirasol, which will be made available on SEDAR at www.sedar.com within the next 45 days.  Methods used by NCL in the current resource estimate are in general similar to those used in the previous estimate (as posted on SEDAR on June 23, 2011).

Paul G. Lhotka, Principal Geologist for Mirasol, and the Qualified Person for Mirasol under NI 43-101, has summarized and approved the technical content of this news release and the drilling results presented here which are not included in the updated resource estimate.

Quality Assurance/Quality Control:
Coeur d'Alene operates the Joaquin Joint Venture and generated the drilling data used in this news release and reported it to Mirasol.  Drill core samples were submitted to Alex Stewart (Assayers), Argentina S.A. and ALS Laboratories, both ISO 9000-2000 accredited laboratories located in Mendoza, Argentina. Gold and silver results were determined using standard fire assay techniques on a 30 gram sample with a gravimetric finish for gold and silver. Coeur's QAQC program includes the insertion of blanks, standards and duplicates into the sample stream for Joaquin drill holes. Mirasol has performed an independent analysis of the QAQC data generated by Coeur. Dr. Paul Lhotka has reviewed the Coeur data, calculated the intercepts in this news release, and is a qualified person as defined by National Instrument 43-101.

Assay results from subsurface drill core or RC drill samples may be higher, lower or similar to results obtained from surface samples.

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

Appendix 1. Complete Results of Drill Intercepts Not Included in the Current Resource Estimate

• Silver equivalent is calculated as AgEQ g/t = Ag g/t + 65 x Au g/t. Metallurgical recoveries are assumed to be 100%.
• Primary intersections are calculated at a cutoff grade of 20 g/t with some internal dilution allowed at the discretion of the project's Qualified Person.
• "Included" intersections are calculated at a 50 g/t or higher cutoff grade.
• Reported grades are not capped.
• Estimated true widths have not been calculated and the AgEq gram metre product is thus based on the uncorrected core lengths of the intercepts
• + indicated holes are considered preliminary pending QA/QC data for certified standards
• # indicated hole is pending a single assay which has been assumed to have zero grade herein
• ^ the two indicated holes have 5m gaps in sampling which are assumed to have zero grade herein

Appendix 2. Joaquin Project -- Locations of Holes not Included in Current Resource Estimate (includes previously published DDJ- 253 and 254)

* previously published
GKCI = Gauss Kruger Campo Inchauspe coordinates

SOURCE Mirasol Resources Ltd.