Mansfield Minerals Inc.

Mansfield Minerals Inc.

January 31, 2007 17:01 ET

Mansfield Minerals Inc.: Trenching Defines North Zone Target at Rio Grande Copper-Gold Project, NW Argentina

VANCOUVER, BRITISH COLUMBIA--(CCNMatthews - Jan. 31, 2007) - Mansfield Minerals Inc. (TSX:MDR) -

Mansfield Minerals Inc. (the "Company") has received assay results from its joint venture partner, Antares Minerals Inc. (TSX VENTURE:ANM), for the first 5 trenches of a 25 trench, 5,200 metre program at the Company's Rio Grande copper-gold project in Salta Province, north-western Argentina. The results are from the previously poorly exposed North Zone target area; highlights include: Trench T-42 - 48 metres with 0.47 g/t Au and 0.29% Cu, Trench T-44A - 54 metres with 0.48 g/t Au and 0.37% Cu (0.2% Cu cut-off).

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

These results clearly delineate the surface expression (0.1% Cu cut-off) of the North Target as a 60-200 metre wide zone that extends for more than 800 metres to the west of the Sofia Zone where recent drilling has encountered encouraging results beneath similar surface manifestations (RGA-06-024 - 128 metres with 0.71 g/t Au and 0.47% Cu; RGA-060026 - 158 metres with 0.51 g/t Au and 0.46% Cu - see press release of September 5, 2006). The North Zone remains open to the southwest and possibly to the north beneath colluvial cover.

The current trenching program has been highly successful at penetrating extensive thin colluvial cover with bedrock exposed along more than 85% of the trench lengths. The effectiveness of the trenching was considerably greater than anticipated and the trenching program was therefore extended to 5,200 metres from the originally planned 4,400 metres. Results have been received from 1,696 metres of trenches sampled in December. Sampling of the remainder of the trenches is ongoing and should be completed in February with analytical results anticipated in March.

Copper-gold mineralization at Rio Grande occurs within a distinct two-kilometre 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 1,500 metres long, 80-200 metres wide, with a minimum depth of 200 metres. Mineralization remains open in both directions along strike and to depth. The remaining two-thirds of the ring zone exhibits only minor outcrop exposure and has received limited work to date. A total of 22 trenches have been cut at approximately 150 metre spacing to provide better exposure along the northern, western and southern margins of the system. Additional trenching is also being completed at the Northeast Target; a distinct gold-copper soil anomaly associated with a magnetic/IP chargeability anomaly located approximately 2 kilometres to the northeast of the principal Rio Grande area.

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

"The current trenching program at Rio Grande has proven to be very effective at exposing bedrock and has nicely defined the North Zone target where we have had minimal previous exploration. The surface expression of the North Zone target is more robust that we anticipated given that it is approximately 200 metres higher in elevation than the Discovery Zone. We have increased the size of the trenching program as it provides very cost-effective data that will maximize the chances of success when we begin to drill later this season."

Catua Project, Jujuy Province, Argentina: Antares has completed an eight-hole (1,379 metre) drilling program at the Company's Catua exotic copper-oxide project in Jujuy Province, Argentina. The program was designed to test for a buried porphyry copper source for an extensive lens of exotic copper-oxide mineralization exposed in a younger cover sequence at the surface. Three deeper holes (303.1-401 metres) tested IP chargeability highs interpreted to be possible copper-iron sulphides beneath post-mineral cover and five shallow holes (24.5-100 metres) tested for possible stacked lenses of exotic copper-oxide mineralization beneath the known occurrence. All of the holes encountered a thick continental red bed sequence of clastic sediments with no visible evidence of porphyry copper style mineralization. No definite pre-mineral basement rocks were encountered to the depths drilled. The sub-horizontal lens of exposed exotic copper-oxide mineralization appears to be thin (1-3 metres thick) and no additional lenses were encountered at depth. Antares is currently reviewing all available data sets to determine if additional exploration at the Catua property is warranted.

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 260 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). Antares can earn up to a 60% interest in the Rio Grande property from Mansfield by completing certain work expenditures, making certain payments and issuing shares to Mansfield over a four-year period (see Mansfield press release dated July 14, 2004).

On behalf of the Board of Directors,

Gordon P. Leask, P.Eng., President

All of Antares' exploration programs and pertinent disclosure of a technical or scientific nature are prepared by or prepared under the direct supervision of John Black, Antares' President, who serves as the qualified person (QP) under the definitions of National Instrument 43-101. A section of the Antares website is dedicated to sampling, assay, and quality control procedures. Mineral resources do not have demonstrated economic viability and future in-fill drilling and scoping, pre-feasibility and feasibility studies will determine what percentage of the inferred resource can be placed into the mineable category. Antares is not aware of any environmental, permitting, legal, title, taxation, socio-political, marketing or other issue which may materially affect this estimate of mineral resources.

Certain disclosure in this release, including management's assessment of Antares' plans and projects, constitutes forward-looking statements that are subject to numerous risks, uncertainties and other factors relating to Antares' operation as a mineral exploration company that may cause future results to differ materially from those expressed or implied. Readers are cautioned not to place undue reliance on forward-looking statements.

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

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