Mansfield Minerals Inc.

Mansfield Minerals Inc.

April 17, 2007 13:00 ET

Mansfield Minerals Inc.: Aggressive Drill Program Funded at Rio Grande, NW Argentina

VANCOUVER, BRITISH COLUMBIA--(CCNMatthews - April 17, 2007) - Mansfield Minerals Inc. ("Mansfield" or the "Company") (TSX VENTURE:MDR) and its joint venture partner, Antares Minerals Inc. ("Antares") (TSX:ANM), have executed a vesting agreement whereby Antares will undertake to vest its 50% interest in the Rio Grande property by completing US$3,375,000 in exploration expenditures and issuing a further 300,000 shares of Antares to Mansfield on or before September 30, 2007. Antares has spent approximately US$2,700,000 on Rio Grande to date pursuant to the terms of the Letter of Understanding between the two companies dated June 30, 2004 (the "LOU").

In addition, Mansfield will subscribe for $5,250,000 of treasury units of Antares at $1.75 per unit, each unit consisting of one common share and one-half of a common share purchase warrant, with each full warrant exercisable at $2.25 for one year. At the same time, Mansfield will issue to Antares, 3 million warrants exercisable at $4.00 for one year (the "Initial Mansfield Warrants") and a further 1.5 million warrants exercisable at $4.75 per share for a period of two years, subject to the Initial Mansfield Warrants being exercised. In consideration of Mansfield subscribing to the private placement and granting the warrants to Antares, Antares has agreed to spend an additional US$375,000 to earn a 50% interest in Rio Grande and to forfeit its right to acquire a further 10% interest in the property by spending an additional US$1,500,000 on the property, and Mansfield has released Antares from its obligation to make further cash payments of $375,000 and issue an additional 300,000 common shares to Mansfield, all as contemplated in the LOU.

Subsequent to the closing of the above private placement, Mansfield and Antares plan to commence a 15,000 metre drilling campaign at Rio Grande with Antares funding the program until the completion of its US$3,375,000 vesting obligation. Thereafter, the parties will fund the completion of this and subsequent programs on a 50/50 joint venture basis with Antares as operator.

The above transactions are subject to regulatory approval.

About the Rio Grande Project, Salta Province, Argentina

The Rio Grande project is very favourably located along the prominent northwest-trending Archibarca Lineament which also controls the location of the world-class giant Escondida porphyry copper deposit 150 km to the northwest in Chile. The Rio Grande project shares many geologic similarities with the Bajo de Alumbrera porphyry copper-gold deposit which is located along a similar northwest-trending regional structural lineament approximately 300 km to the south.

Copper-gold mineralization at Rio Grande occurs within a distinct two-km diameter ring fracture zone defined by IP chargeability and anomalous surface copper and gold soil geochemistry. Exploration to date has focused on the better exposed Discovery and Sofia zones along the south-eastern portion of the system. Drilling and trenching in these areas has defined a copper-gold mineralized zone 1500 m long, 80-200 m wide, with a minimum depth of 200 m. Mineralization remains open in both directions along strike and to depth. An extensive trenching program completed by Antares earlier this year was successful in identifying additional drill targets on the property.

About Mansfield Minerals Inc.

Mansfield is a mining exploration company which has focused its activities in northwestern Argentina since August 1994. The Company's current significant properties and projects consist of mineral rights covering approximately 190 square miles in three Argentine provinces and one Canadian province. The Company is currently focused on three primary projects which include Lindero (gold), Rio Grande (copper-gold) and La Frontera (silver-gold).

This news release has been reviewed by Gordon P. Leask, P.Eng., President of the Company, and a Qualified Person ("QP") as defined by National Instrument 43-101 (Standards of Disclosure for Mineral Projects).

On behalf of the Board of Directors,

Gordon P. Leask, P.Eng., President

We Seek Safe Harbor.

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

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