Mansfield Minerals Inc.

Mansfield Minerals Inc.

June 04, 2007 14:30 ET

Mansfield Minerals Inc.: Drilling Program Commences at Rio Grande, Argentina

VANCOUVER, BRITISH COLUMBIA--(Marketwire - June 4, 2007) - Mansfield Minerals Inc. (TSX VENTURE:MDR) -

Mansfield Minerals Inc. (the "Company" or "Mansfield") announces that its joint venture partner, Antares Minerals Inc. ("Antares") (TSX VENTURE:ANM), has commenced a 15,000 metre diamond drill program on the Rio Grande copper-gold porphyry project in northwestern Argentina. Antares is earning a 50% interest in the Rio Grande project pursuant to a letter of understanding with Mansfield and will complete the required expenditures to vest its 50% interest in the property within the next 30 days. Upon vesting, Antares and Mansfield will enter into a definitive joint venture agreement to fund ongoing development at Rio Grande on a 50/50 basis with Antares as the operator.

Two rigs are currently drilling and a third rig has just arrived on the property and will commence drilling within the next few days. The objectives of the program are 1) to follow-up on encouraging results from previous drilling campaigns in the Sofia and Discovery Zones, 2) to drill test the remaining two-thirds of the system that has not been adequately explored to date, and 3) to provide an initial drill test of the satellite Northeast Target which bears geological and geochemical similarities to Mansfield's nearby 100% owned Lindero gold deposit.

Antares has received all assay results from its 2006-07 trenching program (25 trenches, 4646 metres of bedrock) and significant new results are as follows:

- The Discovery Zone has been extended approximately 100 metres to the west with results from Trench 57A (20m of 0.24 g/t Au and 0.28% Cu) and Trench 57B (30m of 0.56 g/t Au and 0.36% Cu, plus 24m of 0.48 g/t Au and 0.46% Cu, plus 30m of 0.35 g/t Au and 0.46 Cu).

- The North Zone has been extended by 150 metres to the west with Trench 47 (16m with 0.41 g/t Au and 0.36% Cu and 10m with 0.31 g/t Au and 0.26% Cu).

- Trench 53 exposed 63 metres of 0.39 g/t Au and 0.57% Cu in the Sofia zone immediately above the drill fan that includes RGA-06-24 and RGA-06-26.

- Trench 56 intersected anomalous gold values (28m of 0.21 g/t Au and 26m of 0.14 g/t Au with individual 2m intervals of up to 0.5 g/t Au) associated with quartz-magnetite veining in intermediate intrusive rocks along the eastern margin of the Northeast Target.

The majority of the previously unreported trenches are located inboard of the projected mineralized ring fracture along the western and northern portions of the system and did not expose significant areas of mineralization. Thicker colluvial cover prevented effective trenching across the most favorable portions of the western side of the system.

In addition, the Company has received notice from Antares that it is terminating its letter of understanding on the Catua property and has returned the project to the Company.

This news release was reviewed and the contents have been verified by Gordon P. Leask, P.Eng., President, Director and CEO of the Company and a Qualified Person as defined by National Instrument 43-101 (Standards of Disclosure for Mineral Projects).

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).

On behalf of the Board of Directors,

Gordon P. Leask, P.Eng., President

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

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