VANCOUVER, BRITISH COLUMBIA
-- (MARKET WIRE)
-- 06/15/11
Rio Alto Mining Limited ("Rio Alto" or the "Company") (TSX VENTURE: RIO)(OTCQX: RIOAF)(BVLAC: RIO)(DBFrankfurt: MS2) is pleased to report assay results from 18 reverse circulation ("RC") drill holes within and around the Calaorco Pit at the La Arena Gold Oxide Mine ("Oxide Mine") located in Peru.
Significant intercepts were:
Hole Intercept (mts) Gold Grade (g/t)
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CA-R11-018 184 0.84
CA-R11-020 134 2.29
CA-R11-021 274 0.51
CA-R11-022 200 1.43
CA-R11-024 296 0.69
CA-R11-025 210 0.62
Rio Alto previously announced an 11,700m RC drilling program at the Calaorco Pit. Based on the results obtained from the first 32 holes totaling 9,029m management has decided to increase the program by 3,000m to 14,700m in approximately 55 holes. Rio Alto will deliver an updated resource model for the Calaorco Pit during Q4 2011. Management expects that this drilling program will: result in positive changes to the resource block classification; define new resource blocks; and identify new areas to test in order to increase resources.
On April 26, 2011 the Company reported the results from 14 holes totaling 3,755m. This announcement reports the results of an additional 9,029m in 18 holes. All holes, except one, intercepted gold mineralization in excess of the current mining cutoff grade within and outside of the current pit design.
The results of the most recent 18 holes within the oxide breccia sandstone are outlined below:
Drill Results
References to "Pit Location" in the following table refer to intercepts within ("Inside") the Calaorco Oxide Pit or drill hole intercepts that extended below ("Below") the Calaorco Oxide Pit. A map illustrating drill hole locations and selected drill hole cross sections related to this press release may be accessed by following this link http://media3.marketwire.com/docs/0615rio.pdf.
Hole ID From To Interval (m) Au g/t Ag g/t Pit Location
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RC15 88 104 16 0.41 0.40 Inside
RC16 182 200 18 0.33 0.92 Inside
RC17 0 40 40 3.44 0.28 Inside
Including 18 34 16 6.08 0.33 Inside
RC17 112 166 54 0.36 0.21 Inside
RC17 236 300 64 0.38 0.33 Inside
RC18 0 184 184 0.84 0.30 Below
Including 18 54 36 2.17 0.29 Inside
RC19 122 150 28 0.25 0.52 Inside
RC20 4 138 134 2.29 0.59 Inside
Including 48 60 12 6.00 0.42 Inside
Including 104 114 10 6.12 0.62 Inside
RC21 0 274 274 0.51 0.51 Below
Including 56 70 14 2.52 0.96 Inside
RC22 0 20 20 0.28 0.21 Inside
RC22 88 288 200 1.43 0.26 Below
Including 132 186 54 3.55 0.32 Inside
Including 174 182 8 16.02 0.20 Inside
RC23 4 32 28 0.56 0.21 Inside
RC23 54 78 24 0.60 0.79 Inside
RC23 100 162 62 0.29 0.30 Inside
RC23 178 196 18 0.58 0.56 Inside
RC23 218 252 34 0.28 0.42 Below
RC24 2 298 296 0.69 0.41 Below
RC25 0 210 210 0.62 0.26 Below
Including 80 94 14 3.05 0.26 Inside
RC25 242 260 18 0.45 0.20 Below
RC26 72 106 34 0.72 0.62 Inside
Including 74 76 2 8.13 2.40 Inside
RC26 246 300 54 0.32 0.41 Inside
RC27 214 336 122 0.37 0.37 Below
RC28 18 264 246 0.33 0.42 Below
Including 22 26 4 1.61 1.35 Inside
Including 102 108 6 1.47 0.33 Inside
Including 220 226 6 1.06 0.67 Below
RC29 10 28 18 0.45 0.20 Inside
RC29 104 146 42 0.19 0.58 Inside
RC30 0 34 34 0.11 0.20 Inside
RC30 86 106 20 0.13 0.34 Inside
RC30 164 178 14 0.22 0.23 Inside
RC30 264 306 42 0.20 0.31 Below
RC31 Below the cutoff grade
RC32 32 54 22 0.22 1.18 Inside
There are two RC drill rigs working at La Arena. By the end of June, four diamond drill rigs are scheduled to arrive on site.
Approximately 500m north of Calaorco a new exploration target, Astrid, has been identified by surface mapping and geochemical sampling. This target has the same geological and geochemical characteristics as Calaorco. At Astrid the Company plans to run 20 Km of IP and Ground Magnetic lines to identify drill targets.
Quality Control and Assurance
Sampling of the reverse circulation drilling and sample preparation were performed by Rio Alto personnel and were carried out under strict protocols recommended in the NI 43-101 Technical Report dated July 31, 2010 prepared by Coffey Mining Pty Ltd for the Company ("the Report"). Samples were taken every 2m and split in half to yield seven to ten kilogram samples. Drill sample recovery was generally in excess of 90 %. Rio Alto has a rigorous QA/QC program to control the chain-of-custody of samples and the insertion of blanks, duplicates, and certified reference standards in each batch of samples. Samples were shipped to CIMM-Peru in Lima where they were dried, crushed, pulverized, and assayed. All gold assays were obtained by standard 50g fire assaying with AA finish. All silver assays reported in the press release were obtained by Aqua-Regia dissolution followed by ICP measurement. CIMM-Peru is an ISO 9001:2000 certified laboratory.
Enrique Garay, M Sc. P. Geo. (AIG Member), Vice President Geology of Rio Alto is the Qualified Person responsible for the management of the exploration program and disclosure of the drill results as defined by National Instrument 43-101. Mr. Ian Dreyer, B.App.Sc (AUSIMM Member), of Coffey Mining Pty Ltd, a Qualified Person as defined by National Instrument 43-101, designed and reviewed the Quality Control and Assurance program carried out by the Company with respect to these drill results. Each of Mr. Garay and Mr. Dreyer has read and approved the scientific and technical information in this news release. For additional information regarding the Oxide Mine please refer to the Report, a copy of which is available under Rio Alto's SEDAR profile at www.sedar.com
This news release contains certain forward-looking information including statements concerning the expected timing for the arrival of drills at La Arena, the timing of a new resource estimate for Calaorco and the announcement of an exploration program at the Astrid target. All statements included herein, other than statements of historical fact, are forward-looking information and such information involves various risks and uncertainties. There can be no assurance that such information will prove to be accurate, and actual results and future events could differ materially from those anticipated in such information. A description of assumptions used to develop such forward-looking information and a description of risk factors that may cause actual results to differ materially from forward-looking information can be found in Rio Alto's disclosure documents on the SEDAR website at www.sedar.com. Rio Alto does not undertake to update any forward-looking information except in accordance with applicable securities laws.
To learn more about Rio Alto Mining Limited, please visit: www.rioaltomining.com or Rio Alto's SEDAR profile at www.sedar.com.
ON BEHALF OF THE BOARD OF RIO ALTO MINING LIMITED
Alex Black, President & COO
Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts the responsibility for the adequacy or accuracy of this release.
Contacts:
Rio Alto Mining Limited
Alex Black
President & COO
+51 1 625 9900 or +51 99279 4655
alexb@rioaltomining.com
Rio Alto Mining Limited
Alejandra Gomez
Investor Relations
+1 604 628 1401 or +1 866 393 4493
alejandrag@rioaltomining.com
www.rioaltomining.com
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