Cornerstone and Thundermin Announce 66% Increase in Indicated and 61% Increase in Inferred NI 43-101 Compliant Mineral Resources at the Little Deer Copper Deposit, Newfoundland

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Cornerstone and Thundermin Announce 66% Increase in Indicated and 61% Increase in Inferred NI 43-101 Compliant Mineral Resources at the Little Deer Copper Deposit, Newfoundland
Marketwire.com - Jun 22, 2011

MOUNT PEARL, NEWFOUNDLAND--(Marketwire - June 22, 2011) -Cornerstone Capital Resources Inc. ("Cornerstone") (TSX VENTURE:CGP) (FRANKFURT:GWN) (BERLIN:GWN) (PINK SHEETS:CTNXF) and 50% joint venture partner Thundermin Resources Inc. ("Thundermin") (TSX:THR) announce the results of an updated mineral resource estimate for the Little Deer Copper Deposit ("Deposit") which is located approximately 10 km north of Springdale in north-central Newfoundland. The updated mineral resource estimate was prepared by P&E Mining Consultants Inc. ("P&E") of Brampton, Ontario, Canada and complies with National Instrument 43-101 ("NI 43-101") (see Table 1).

Highlights

66% increase in the Indicated Mineral Resource to 99.8 million lbs of copper 1,911,000 t grading 2.37% Cu
61% increase in the Inferred Mineral Resource to 175.9 million lbs of copper 3,748,000 t grading 2.13% Cu
Potential to further increase mineral resources with additional drilling below and to the west of the current resources remains strong.

Brooke Macdonald, President of Cornerstone, said "The updated mineral resource estimate represents a substantial increase, and we are very pleased to have met our goal of establishing five to six million tonnes of potentially economic grade copper mineralization. Results of the internal scoping review, also being carried out by P&E, are expected to be received by June 30th. This study is evaluating a range of potential mining and operating scenarios for the project and will provide management with preliminary information on the economic viability of developing a new copper mine at Little Deer".

Table 1: Summary of Little Deer Mineral Resources (P&E, June 20, 2011)
Resource Classification/Zone Tonnes Cu % Cu lbs (M )
Indicated Mineral Resources
Little Deer Zone 1,911,000 2.37 99.8
Inferred Mineral Resources
Little Deer Zone 1,240,000 1.93 52.8
Footwall Zone 1,711,000 2.04 77.0
Footwall Zone Splay 797,000 2.64 46.2
Total Inferred Resources 3,748,000 2.13 175.9

Notes:

1) Mineral resources which are not mineral reserves do not have demonstrated economic viability. The estimate of mineral resources may be materially affected by environmental, permitting, legal, title, taxation, socio- political, marketing, or other relevant issues.

2) 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.

3) The mineral resources in this press release were estimated using the Canadian Institute of Mining, Metallurgy and Petroleum (CIM), CIM Standards on Mineral Resources and Reserves, Definitions and Guidelines prepared by the CIM Standing Committee on Reserve Definitions and adopted by CIM Council.

4) Ordinary Kriging was used for Cu grade interpolation.

5) Grade capping of 15% Cu utilized on composites.

6) A variable bulk density based on numerous field measurements was used for tonnage calculations.

7) A copper price of US$3.42/lb (May 31 2011 24 month trailing average) and an exchange rate of US$0.95=C$1.00 was utilized to derive the 1% Cu cut-off grade. Mining costs were C$40/t, process costs were C$15/t and G&A was C$5/t. Concentrate freight and smelter treatment charges were C$10/t mined. Concentrate mass pull was 7%, process recovery was 97%, smelter payable was 96% and Cu refining was US$0.07/lb.

The updated mineral resource estimate for the Deposit is based on assay results from 48,432 m of drilling in 82 holes completed by Thundermin and Cornerstone since June 2007 and assay data from a total of 102 surface and 122 underground historical holes that were drilled by British Newfoundland Exploration Company ("BRINEX") between 1961 and 1970 and Mutapa Gold Corporation between 1998 and 2000. The historical information was recovered from the archives of the Newfoundland and Labrador Department of Natural Resources in St. John's, Newfoundland.

P&E undertook a new cross sectional interpretation on approximately 10 m centers for the entire Deposit and created a wireframe model of the 3-D solids in order to determine an overall shape and volume for the Deposit. Copper grade data for all samples assayed by Cornerstone and Thundermin from the 2007 to 2011 drill programs and all copper grade data recovered from the historical drilling were used to calculate copper grade estimates for the Deposit. Bulk density data collected by Cornerstone and Thundermin from the 2007 to 2011 drill programs was utilized for the calculation of bulk densities for the entire Deposit.

The substantial increase in tonnage in P&E's updated mineral resource estimate for the Deposit results from a reinterpretation of the sectional data for the Deposit, the inclusion of all of the historical assay data recovered from the archives, the inclusion of assay data for 25 holes drilled by Cornerstone and Thundermin since December 1, 2010 and the use of length-weighted bulk density data for individual assay samples that was not used previously.

Qualified Persons

The updated mineral resource estimate was prepared under the supervision of Mr. Eugene J. Puritch, P. Eng., President of P&E. Mr. Puritch is an independent Qualified Person ("Q.P.") in accordance with NI 43- 101 and has reviewed and approved the contents of this news release. An NI 43-101 compliant Technical Report covering the updated mineral resource estimate is currently being prepared by P&E and will be filed on SEDAR by Cornerstone and Thundermin within 45 days of this news release.

Mr. Andrew Hussey, P.Geo., Project Geologist and Lands Manager, Cornerstone Resources Inc., is the Q.P. responsible for supervising the drilling program on the Little Deer property for the purposes of NI 43-101. Mr. Hussey has also reviewed and approved the contents of this news release.

Metallurgy

On October 19, 2010, excellent metallurgical results from scoping level test work on core samples from the Deposit were announced. This work, which was undertaken at SGS Lakefield Research Limited ("Lakefield") of Lakefield, Ontario, indicates that a saleable, high grade copper concentrate grading over 28% copper with over 97% recovery and free of any deleterious elements can be produced from the Deposit.

Infrastructure

The Deposit is located on a brownfield site and is well situated to take advantage of Newfoundland's developed infrastructure. The Deposit lies approximately 16 km from the Trans Canada Highway and is easily accessed by a 10 km network of paved and gravel roads north of Springdale, where there is an available skilled mining workforce. The site is approximately 8 km from a major power substation and there is a plentiful supply of fresh water in the area. The former tailings impoundment facility for the Whalesback mine, which may be able to be upgraded and used to store additional tailings, is located only 1.2 km north of the Deposit. There is also good access to several deep water ports for any future shipment of copper concentrates. The Duck Pond base metal concentrator, which is owned by Teck Resources Inc., is located approximately 165 km by paved and gravel roads from the Little Deer site, 70 km of which is along the Trans Canada Highway and 65 km of which is on a secondary paved road.

The recovery of archived data has also given us a better understanding of the underground infrastructure that exists on the property. This infrastructure dates from 1966 to 1972 and 1972 to 1974 when a portion of the upper part of the Deposit was developed and mined by BRINEX and Green Bay Mining Company ("Green Bay"), respectively. BRINEX accessed the Deposit from the adjoining Whalesback Mine, which is also controlled by Cornerstone and Thundermin, and Green Bay accessed the Deposit via a ramp. This existing infrastructure may potentially afford substantial cost savings for access underground for future definition drilling and mining.

Little Deer Joint Venture

Cornerstone and Thundermin, the operator, have the option, on a 50/50 basis to earn a 100% interest in the Deposit and adjacent property from Weyburn Investments Ltd. Thundermin, under its joint venture agreement with Cornerstone, has the right to increase its interest in the Little Deer property to 75% by completing a feasibility study and by arranging 100% of the necessary bank financing required to place the property into commercial production. Details on the Deposit and the terms of the agreement with Weyburn can be found in numerous news releases between May 1, 2007 and June 16, 2011 and on Cornerstone's and Thundermin's respective websites and on SEDAR.

Junior Exploration Assistance Program

Cornerstone and Thundermin would like to acknowledge the financial support received from the Junior Exploration Assistance (JEA) Program of the Province of Newfoundland and Labrador in carrying out a portion of their work on the Little Deer property.

Other News

In other news, Cornerstone wishes to remind its shareholders and the public that its upcoming Annual General Meeting will be held on Thursday, June 23rd at 11 A.M. (Newfoundland Standard Time) at the Johnson GEO CENTRE located at 175 Signal Hill Road, St. John's. All those interested are cordially invited to attend.

About Cornerstone

Cornerstone Capital Resources Inc. is a mineral exploration company based in Mount Pearl, Newfoundland and Labrador, Canada, with a diversified portfolio of projects in Canada, Ecuador and Chile, and a strong technical team that has proven its ability to identify, acquire and advance properties of merit. The company's business model is based on generating exploration projects whose subsequent development is funded primarily through joint venture partnerships. The company is well funded and commitments from JV partners constitute significant validation of the strength of Cornerstone's projects.

Investors can access and join the following Cornerstone social media channels:

Facebook (http://www.facebook.com/cornerstoneresourcesinc)

Twitter (http://twitter.com/Cornerstone_cgp)

YouTube channel (http://www.youtube.com/user/CornerstoneResource)

Flickr (http://www.flickr.com/photos/cornerstoneresources)

The link to recent CEO audio interviews is: http://www.cornerstoneresources.com/s/Interviews.asp

The link to a recent Corporate presentation with narration is:

http://rblcommunications.com/resources/CGP/1/CGPmay2011.html

Cautionary Notice:

This news release may contain 'Forward-Looking Statements' that involve risks and uncertainties, such as statements of Cornerstone's plans, objectives, strategies, intentions and expectations. The words "potential," "anticipate," "forecast," "believe," "estimate," "expect," "may," "project," "plan," and similar expressions are intended to be among the statements that identify 'Forward-Looking Statements.' Although Cornerstone believes that its expectations reflected in these 'Forward-Looking Statements' are reasonable, such statements may involve unknown risks, uncertainties and other factors disclosed in our regulatory filings, viewed on the SEDAR website at www.sedar.com. For us, uncertainties arise from the behaviour of financial and metals markets, predicting natural geological phenomena and from numerous other matters of national, regional, and global scale, including those of an environmental, climatic, natural, political, economic, business, competitive, or regulatory nature. These uncertainties may cause our actual future results to be materially different than those expressed in our Forward- Looking Statements. Although Cornerstone believes the facts and information contained in this news release to be as correct and current as possible, Cornerstone does not warrant or make any representation as to the accuracy, validity or completeness of any facts or information contained herein and these statements should not be relied upon as representing its views subsequent to the date of this news release. While Cornerstone anticipates that subsequent events may cause its views to change, it expressly disclaims any obligation to update the Forward- Looking Statements contained herein except where outcomes have varied materially from the original statements.

On Behalf of the Board,

H. Brooke Macdonald, President

Neither 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.