Mansfield Minerals Inc.

Mansfield Minerals Inc.

September 14, 2007 08:30 ET

Mansfield Minerals Inc.: Rio Grande Stepout Intersects 189 m With 0.70% Cu and 0.67 g/t Au

VANCOUVER, BRITISH COLUMBIA--(Marketwire - Sept. 14, 2007) - Mansfield Minerals Inc. (TSX VENTURE:MDR) (the "Company") announces that its joint venture partner, Antares Minerals Inc. ("Antares") has reported results from the initial eight holes (3,574 metres) of the 15,000 metre drilling program at the Rio Grande copper-gold project in northwestern Argentina.

Drill hole RGA-07-034 intersected a 189 metre interval with 0.70% Cu and 0.67 g/t Au commencing at a depth of 140 metres. This is the best intersection to date at the Rio Grande project and the hole is located immediately to the northwest of the two previous best holes. RGA-07-034 is 150 metres north of RGA-06-026 (158 m with 0.46% Cu and 0.51 g/t Au) and 180 metres northwest of RGA-06-024 (128 m with 0.47% Cu and 0.71 g/t Au). The mineralization in RGA-07-034 was encountered at a shallower depth than anticipated and remains open to the west and north. These eight holes were completed in the Sofia and Discovery zones and were primarily drilled to test for extensions of mineralization to depth and along strike. Seven of the eight holes intersected copper-gold mineralization but the highlight of the program has been drill-hole RGA-07-034 at the northern end of the Sofia zone. In addition, there are five more contiguous drill holes and three surface trenches containing moderate to high-grade intervals of copper-gold mineralization comprising an open zone which is 350 metres in strike length.

A total of 21 holes (9,607 metres) has been completed to date and three drill rigs are currently drilling. Assay results are pending on the remaining holes.

Gordon P. Leask, President and CEO of Mansfield Minerals Inc., commented as follows:

"Drill hole RGA-07-34 elevates the significance of contiguous holes RGA 14 to 16, 24, 26 and 30. We now have strike and dip extensions with feeder zone grades. As our geologic understanding of the deposit has increased, so has the drill success. For good projects it has been said "The more you work them, the better they get". This is certainly the case for Rio Grande."

John Black, President and CEO of Antares Minerals Inc., commented as follows:

"We are very pleased with the results from the first few holes of the current drilling campaign at Rio Grande. The drilling continues to define a large zone of copper-gold mineralization at the now continuous Discovery-Sofia zones. More importantly, the strong and relatively near-surface intercept in RGA-07-034 has extended the zone of higher grade copper-gold mineralization at the northern end of Sofia zone an additional 150 m to the north. This is the best drill intercept to date at Rio Grande and there is room to extend the mineralization to the west and north towards the North zone target area. Drilling continues with three rigs and is currently focused on completing holes into the previously untested North zone. We look forward to providing additional results in the near future."

Rio Grande Project, Northwestern Argentina
Highlights of Drilling Results
Hole Copper Gold
Number Zone Interval Length (%) (g/t)
RGA-07-29 Sofia-Discovery 160-200 m 40 m 0.29 0.29
RGA-07-30 Sofia Deep 425-437 m 12 m 0.37 0.33
491-508 m 17 m 0.69 0.95
Sofia-Discovery 72-84 m 12 m 0.28 0.33
RGA-07-31 Connection 98-158 m 60 m 0.24 0.32
Discovery Deep 306-338 m 32 m 0.41 0.30
RGA-07-32 348-362 m 14 m 0.49 0.38
564-575 m 11 m 0.30 0.29
RGA-07-33 Discovery South No significant value
Sofia North 140-329 m 189 m 0.70 0.67
RGA-07-34 incl. 146-173 m 27 m 1.16 1.59
incl. 241-253 m 12 m 2.20 1.85
RGA-07-35 Discovery South 103-133 m 30 m 0.32 0.21
RGA-07-36 Discovery Deep Assays pending
Discovery South 188-201 m 13 m 0.30 0.35
RGA-07-37 217-231 m 14 m 0.25 0.20
237-257 m 20 m 0.36 0.21

A map of the drill hole locations has been posted on the Company's website and can be viewed at

This news release has been reviewed by John Black, Antares' President, who serves as the qualified person (QP) under the definitions of National Instrument 43-101. Antares' security, chain of custody and quality control is described on their website and can be reviewed at:

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 175 square miles in three Argentine provinces and one Canadian province. The Company is currently focused on two primary projects which include Lindero (gold) and Rio Grande (copper-gold). Antares is earning a 50% interest in the Rio Grande project from Mansfield and reports that it has recently completed the required expenditures and payments, and plans to vest its interest in the near future. Upon vesting, Antares will formalize a definitive joint venture agreement with Mansfield to fund ongoing exploration at Rio Grande on a 50/50 basis with Antares as operator.

On behalf of the Board of Directors,

Gordon P. Leask, P.Eng. President

For more information please visit our website at

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

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