Initial Resource Estimate For The Joaquin Project
VANCOUVER, BC - Mirasol Resources Ltd. reported the first 43-101 compliant resource estimate for part of the Joaquin Silver Project, Santa Cruz Province, Argentina. The estimate produces an in-pit resource for the La Negra and La Morocha deposits and includes 19.6 million ounces of silver in the Indicated category, and 47.9 million ounces of silver in the Inferred category. Mineralization remains open below the base of drilling at both Morocha and La Negra, showing clear scope for further drilling to increase the size of this initial resource.
The resource estimate was prepared by an independent consulting firm, NCL IngenierÆa y Construcciùn Ltda. ("NCL") of Chile, commissioned by Mirasol's joint venture partner Coeur d'Alene Mines ("Coeur"), and is calculated for two deposits, La Negra and La Morocha, located approximately 1.2 kilometres apart. The estimate was prepared according to NI 43-101 standards and the CIM Standards on Mineral Resources and Reserves: Definitions and Guidelines (CIM 2005).
The resource estimate is based on 136 HQ (63.5mm diameter) diamond drill holes totaling 23,101 metres of which 80 holes (15,490 metres) were drilled at La Negra and 29 holes (4,294 metres) were drilled at Morocha. These holes included 11,662 samples (not including control samples) all assayed for silver and gold by fire assay methods representing 15,408 metres of core. Resources were modelled as oxide and sulphide mineralization types with discreet bodies defined by grade shells. At Morocha, a single tabular body, dipping moderately north-westerly, was defined. At La Negra, a sub-vertical feeder and multiple sub-horizontal bodies were defined. The resources have been reported in a pit model constrained by parameters which were determined by Coeur's Technical Services Group in conjunction with NCL. Sufficient work has not yet been done to classify the resources as reserves, and the parameters used are considered to be preliminary in nature and the resources are not demonstrated to have economic viability at this stage. Results of the resource estimation are tabulated on a project wide basis, as well as separately for the La Morocha and La Negra deposits. Further, they have been broken down by category into those resources categorized as Indicated (with a greater confidence level) and Inferred, and by mineralization type into oxide and sulphide types. Most of the resource is comprised of oxidized mineralization (71% of the silver ounces) with lesser sulphide mineralization (29% of the silver ounces). Based on preliminary, project-specific metallurgical test work and industry experience, Coeur and the independent consultant have determined that lower processing costs can be expected for the oxide mineralization than the sulphide mineralization. Thus, in the pit model oxide mineralization has been assigned a lower cut off grade of 33 g/t silver equivalent, while the sulphide mineralization cut off grade is 51.9 g/t silver equivalent. Sulphide mineralization is however, significantly higher grade on average. The majority of sulphide mineralization is at La Morocha where it occurs beneath oxide mineralization. Project-specific metallurgical test work for metal recovery is at a very preliminary stage at Joaquin. Tests have been performed on the oxide mineralization using leach methods and on the sulphide mineralization by flotation methods for a limited number of samples from both La Negra and La Morocha. The leach tests used industry standard cyanidation with some variations. Cyanidation returned relatively consistent results for La Negra and is more variable for La Morocha. Recent tests using a sulphurous acid pre-leach, prior to cyanidation, have produced the best results at La Morocha of 76% for silver at La Morocha, and 74% recovery of silver at La Negra. Further project-specific leach test work is required to better define recoveries. Based on the test results, and industry experience, Coeur and NCL assumed a 70% oxide recovery for both La Morocha and La Negra in the Whittle Pit parameters. For sulphide material, project-specific flotation test work produced results of 83% recovery of silver at La Negra and 97% recovery of silver at La Morocha. Further project-specific flotation test work is required. Coeur and NCL decided to use a silver recovery of 86% in the Whittle Pit parameters for sulphide mineralization. In addition to the total project resource tabulation at 33 g/t silver equivalent cut-off (oxide) and 51.9 g/t silver equivalent cut-off (sulphide), resources have been tabulated at a series of cut-off grades. This enables construction of grade-tonnage curves which assist in determining the effect on the resource estimates with changes to the cut-off grade. The grade-tonnage curves show the relative importance of the different mineralization types and categories at the present time. The current dominance of oxide resources, considering both tonnes and silver ounces, is clear, but geologically the potential for adding sulphide silver ounces, especially at La Morocha, is of great interest. The company's address is Suite 600-890 West Pender Street, Vancouver, BC V6C 1J9, (604) 602-9989, fax: (604) 609-9946.