MDR Goldrock Mines Corporation

Mansfield Minerals Inc. (the "Company") (TSX VENTURE: MDR) is pleased to announce the SEDAR filing of a National Instrument 43-101 technical report for the recently completed prefeasibility study on its wholly owned Lindero heap leach gold project in northwestern Argentina.

Highlights of the NI 43-101 technical report (previously reported by the Company on March 22, 2010) include:

Pre-tax Project Economics(1)(2)
-------------------------------------------------
Net Present Value
Gold price        (US$ million)      IRR  Payback
($US/oz)        Discount Rate (%)     (%)  (years)
4.0%   6.0%   8.0%
-------------------------------------------------
$850(3)        $237   $194   $157  25.9%      2.8
$975           $363   $305   $256  35.4%      2.2
$1,100         $490   $416   $355  44.1%      1.9

1.  Project economics have been reported by AMEC on a pre-tax basis.
2.  Project economics include a 3% provincial royalty.
3.  Base case project scenario.

--  1.9 million ounces of gold reserves @ 0.19 g/t cut-off.
--  Capital expenditures of US$213 million (includes a US$18 million
contingency).
--  9.5 year mine life with gold production totaling 1.4 million ounces at a
cash cost of US$407/oz.
--  161,000 oz gold average annual production in years 1-5 at a cash cost of
US$373/oz.
--  150,000 oz gold average annual production in years 1-8.

Proceeds of the recently announced private placement financing will be used to rapidly advance the Lindero bankable feasibility study.

Qualified Persons for the NI 43-101 Report

The authors of the NI 43-101 technical report are David G. Thomas (P.Geo.), Jay C. Melnyk (P.Eng.) and Vikram Khera (P.Eng.) of AMEC Americas Limited, Thomas L. Nimsic (P.Geo.) of American Au Ag Associates and Daniel W. Kappes (P.E.) of Kappes, Cassiday & Associates.

The NI 43-101 report can be viewed at www.sedar.com.

ON BEHALF OF THE BOARD OF DIRECTORS,

Gordon P. Leask, P. Eng., President and CEO

Caution Regarding Forward-Looking Statements

This press release includes certain statements that may be deemed "forward-looking statements". All statements in this discussion, other than statements of historical facts, that address future exploration drilling, exploration activities, anticipated metal production, internal rate of return, estimated ore grades, commencement of production estimates and projected exploration and capital expenditures (including costs and other estimates upon which such projections are based) and events or developments that the Company expects, are forward looking statements. Although the Company believes the expectations expressed in such forward looking statements are based on reasonable assumptions, such statements are not guarantees of future performance and actual results or developments may differ materially from those in forward-looking statements. Factors that could cause actual results to differ materially from those in forward-looking statements include metal prices, exploration success, continued availability of capital and financing, and general economic, market or business conditions. Accordingly, readers should not place undue reliance on forward-looking statements.

This news release and the information contained herein does not constitute an offer of securities for sale in the United States and securities may not be offered or sold in the United States absent registration or exemption from registration.

The TSX Venture Exchange has not reviewed and does not accept responsibility for the adequacy or the accuracy of this release.

Contacts: Mansfield Minerals Inc. (604) 681-4462 www.mansfieldminerals.com