Mansfield Minerals Inc.

Mansfield Minerals Inc.

September 28, 2005 09:00 ET

Mansfield Minerals Inc.: Drilling Commences on High-Grade Silver Target at Desierto Gold-Silver Project, Northwestern Argentina

VANCOUVER, BRITISH COLUMBIA--(CCNMatthews - Sept. 28, 2005) - Mansfield Minerals Inc. (TSX VENTURE:MDR) -

Mansfield Minerals Inc. (the "Company") is pleased to announce the commencement of a diamond-drilling program at the Desierto Au-Ag project in Salta Province, northwestern Argentina by its joint venture partner, Antares Minerals Inc. The program will consist of four to six drill holes for a total of approximately 600 m. The drilling will target a 1,200 m long silver-rich vein called the Eastern Silver vein. Surface rock-chip and trench sampling by Antares has returned silver values in excess of 1000 g/t (greater than 32 oz/t) over widths varying from 1-6 meters.

The Eastern Silver vein is one of more than 25 epithermal veins identified to date at the Desierto project. This vein can be traced for more than 1200 m as a linear series of small outcrops, subcrops, and float occurrences of banded quartz-barite vein material. The veins also provide evidence of original base-metal sulphides (galena, pyrite, and sphalerite) that have been oxidized. Initial surface reconnaissance rock-chip sampling by the Company returned highly variable silver and gold values ranging up to 3163.6 g/t Ag and 12.85 g/t Au. In 2003, the Company dug a series of seven trenches to sample the Eastern Silver vein. Three of the trenches were perpendicular to the vein strike and encountered the following true-width intervals of high-grade silver mineralization:

Trench 6 6 m @ 4,785 g/t Ag (154 oz/t),
Trench 5 2 m @ 151 g/t Ag (4.9 oz/t), and
Trench 3 8 m @ 544 g/t Ag (17.5 oz/t)

Two additional trenches also encountered high-grade silver values but were sampled along the vein strike and therefore do not represent true widths:

Trench 2 38 m @ 1154 g/t Ag (37.1 oz/t) and
Trench 7 6 m @ 3123 g/t Ag (100 oz/t)

The vein zone often consists of several sub-parallel veins with individual vein widths of 0.5-3 m and highly variable along strike. Antares confirmed the previous sample results with 5 samples taken across individual veins from Trenches 3 and 6 with the following results:

Trench 6 2.8 m @ 5300 g/t Ag (170 oz/t Ag, true-width) and
1 m @ 2120 g/t Ag (68 oz/t Ag, same vein, 2 m to north,
partial width)
Trench 3 2 m @ 4100 g/t Ag (132 oz/t Ag, true-width),
1 m @ 3820 g/t Ag (123 oz/t Ag, true-width), and
1 m @ 4620 g/t Ag (149 oz/t Ag, true width)

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

"We are very pleased to begin drilling at the Desierto project. This is the first of four projects we plan to drill in the next eight months. The high-grade silver values of the Eastern Silver vein zone represent a compelling target at Desierto and we are optimistic that success with this initial drill campaign will provide a springboard to allow testing of additional gold and silver vein targets on the property."

Desierto Project

The Desierto property is 100% owned by Mansfield Minerals Inc. Under the terms of an option/joint-venture agreement, Antares can earn an initial 50% interest in the project by completing work expenditures totalling US$2,000,000 and making option payments totalling US$400,000 over a four-year period. Antares' commitment for the first year is to spend US$150,000 and make an option payment of US$25,000. Antares may terminate the agreement at anytime thereafter. If Antares completes the 50% earn-in it can elect to earn an additional 10% by issuing 100,000 shares and spending an additional US$1.5 million over 18 months.

The Desierto project is located immediately to the south of the Taca Taca porphyry copper deposit, approximately 320 km to the west of the city of Salta, Salta Province, northwestern Argentina. The project hosts multiple epithermal precious metal veins in three main areas on the property; predominantly gold-bearing veins to the west, predominantly silver-bearing veins to the east, and the Silica Ridge, a prominent rhyolite dyke with locally strong silicification of both the dyke and the wall rocks in the central part of the property. The veins are hosted in dacite tuffaceous rocks and underlying granodiorite intrusive rocks.

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's Lindero deposit has a drill inferred 1,000,000+ ounce gold resource, with expansion drilling to commence in October 2005. Phase II drilling stage has been completed at its Rio Grande gold-copper property, with further drilling planned in January 2006.

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.

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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