Calvista Announces A Significant Upgraded Mineral Resource Estimate

TORONTO, ONTARIO--(Marketwire - Sept. 26, 2012) - Calvista Gold Corporation (TSX:CVZ)(OTCQX:CAGOF) ("Calvista" or the "Company") is pleased to announce the completion of a new technical report which includes increases in the Company's mineral resource estimates for both the Callejón Blanco and Buenavista prospects.

The Company's Chief Executive Officer, Mr. Mark Haywood stated that, "the Company is extremely pleased to report a significant increase of its mineral resources on the La Mascota trend as a result of its Phase II drilling. The new technical report confirms a significant mineral resource increase with more than half the estimate now upgraded to an Indicated Resource. The Company has also defined a number of distinct silver-rich mineralized zones adjacent to our primary gold zones that enhance our overall mineral resources for the project."

Highlights of the new technical report:

• Indicated mineral resources for the Callejón Blanco and Buenavista prospects totalling 4.03 million tonnes grading 3.49 grams per tonne ("g/t") of gold and 15.77 g/t of silver using a cut-off grade of 2.0 g/t of gold (approximately 452,218 ounces of gold and 2,045,770 ounces of silver);
  
  
• Inferred mineral resources for the Callejón Blanco and Buenavista prospects totalling 3.77 million tonnes grading 3.71 g/t of gold and 15.84 g/t of silver using a cut-off grade of 2.0 g/t of gold (approximately 449,023 ounces of gold and 1,917,866 ounces of silver);
  
  
• Plus Inferred resources defined inside a silver-rich mineralized zone at the Callejón Blanco prospect totaling 5.59 million tonnes grading 18.38 g/t silver and 1.75 g/t gold using a cut-off grade of 10.0 g/t of silver (approximately 314,402 ounces of gold and 3,302,121 ounces of silver);
  
  
• The Callejón Blanco and Buenavista targets remain open to expansion at depth;
  
  
• The highest point of our mineral resources occurs more than 500 metres below the Páramo ecosystem elevation limit of 3,200 metres above sea level; and
  
  
• The new technical report and mineral resource estimate was completed by independent expert and Qualified Person, Dr. Vadim Galkine, Ph.D., P. Geo., and is based upon 49 diamond drill holes totaling 20,043 metres.
  
  

The Callejón Blanco and Buenavista targets are considered to have the hallmarks of a porphyry Cu±Mo±Au style Deposit. Gold is hosted in a hydrothermal breccia near the surface, in an intrusive as disseminated mineralization, and also in techtonically controlled high-grade zones associated with corroded quartz veins and sometimes with sulphide mineralization.

Tables showing the Indicated and Inferred Mineral Resource estimates are presented below for various cut-off grades. Highlighted in red, in the tables below, are the cut-off grades considered to be the most appropriate for this target. The resources were estimated using a minimum thickness of 1.5 metres, a dry density of 2.55 g/cm³ for Callejón Blanco and 2.62 g/cm³ Buenavista prospects, respectively.

The mineral resources in the technical report were estimated using the Canadian Institute of Mining, Metallurgy and Petroleum ("CIM") Standards on Mineral Resources and Reserves, Definitions and Guidelines prepared by the CIM Standing Committee on Reserve Definitions.

Mineral resources which are not mineral reserves do not have demonstrated economic viability. Confidence in a mineral resource estimate is insufficient to allow the meaningful application of technical and economic parameters or to enable an evaluation of economic viability worthy of public disclosure. The estimate of mineral resources may be materially affected by environmental, permitting, legal, title, taxation, sociopolitical, marketing, or other relevant issues.

The quantity and grade of reported Inferred Resources in this estimation are uncertain in nature and there has been insufficient exploration to define these inferred resources as an indicated or measured mineral resource and it is uncertain if further exploration will result in upgrading them to an indicated or measured mineral resource category.

Mineral Resource Estimation Methodology

The processing and interpretations of the resource estimation were completed by an independent consultant, Eng Abdiel Diaz Carmona, Ph.D., in collaboration with the Company's Qualified Person, then tested and independently confirmed by the independent expert and Qualified Person Dr. Galkine. All samples were composited into a constant length of 1.5 metres, and the resource estimation was completed using GEMCOM software for variography and for creation of the resource block model with a parent block size of 25m x 25m x 10m (x,y,z), and a sub-block size of 3m x 3m x 3m. Ordinary Kriging was used to estimate gold block grades in the Mineral Resource. The complete details of the kriging methodology adopted are provided in the NI 43-101 technical report being prepared. Although potentially mineable underground shapes have not been defined, the in-situ gold mineral resource is reported at a 2.0g/t gold cut-off grade, which the Company's believes is sufficient to define potentially mineable underground gold resources. All Mineral Resources are reported on a 100% basis for Calvista controlled properties.

Within 45 days, Calvista will file a National Instrument 43-101 compliant technical report with the applicable securities regulatory authorities that supports the technical information contained herein, which will be available for viewing under the corporate profile of Calvista Gold Corporation at www.sedar.com.

Quality Assurance

Calvista has developed and implemented Quality Assurance & Quality Control ("QA&QC") protocols that exceed current exploration industry best practices. Besides the normal QA&QC procedures related to the insertion of blanks, standards, and duplicates, and the use of external laboratories for controls, Calvista has introduced additional QA&QC procedures for all types of work in the company. Sample preparation is conducted by the ALS Group ("ALS") in Bucaramanga, Colombia before being analyzed at the ALS certified assay laboratory in Lima, Peru.

Technical Information

Mr. Ricardo Valls, P. Geo., Calvista's VP Exploration, is the Company's designated Qualified Person for this press release within the meaning of National Instrument 43-101 Standards of Disclosure for Mineral Projects and has reviewed and validated that the technical information contained in the release is accurate.

About Calvista

Calvista is a mineral exploration company focused on the acquisition, exploration and development of properties for the mining of gold and other minerals. All our prospects in the California Valley are located below 3,200 metres and are not affected by the Paramo ecosystem law. With a head office in Toronto and Colombian headquarters in Bucaramanga, Calvista is led by a management team with over 50 years of exploration and mining experience, principally in South and Central America. For further details on Calvista, please refer to our web site (www.calvistagold.com) and Calvista's Canadian regulatory filings on SEDAR at www.sedar.com.

CAUTIONARY STATEMENT: This news release contains forward-looking information, which is not comprised of historical facts. Forward-looking information involves risks, uncertainties and other factors that could cause actual events, results, performance, prospects and opportunities to differ materially from those expressed or implied by such forward-looking information. Forward looking information in this news release includes, but is not limited to, Calvista's objectives, goals or future plans, statements regarding exploration results, exploration p lans and the timing of a potential resource estimate. Factors that could cause actual results to differ materially from such forward-looking information include, but are not limited to, uncertainties inherent to preparing a resource estimate within expected timeline, capital and operating costs varying significantly from estimates, the preliminary nature of metallurgical test results, delays in obtaining or failures to obtain required governmental, environmental or other project approvals, political risks, uncertainties relating to the availability and costs of financing needed in the future, changes in equity markets, inflation, changes in exchange rates, fluctuations in commodity prices, delays in the development of projects and the other risks involved in the mineral exploration and development industry, enhanced risks inherent to conducting business in a jurisdiction such as Colombia, and those risks set out in Calvista's public documents filed on SEDAR. Although Calvista believes that the assumptions and factors used in preparing the forward-looking information in this news release are reasonable, undue reliance should not be placed on such information, which only applies as of the date of this news release, and no assurance can be given that such events will occur in the disclosed time frames or at all. Calvista disclaims any intention or obligation to update or revise any forward-looking information, whether as a result of new information, future events or otherwise, other than as required by law.