Sheffield Resources Ltd.
TSX VENTURE : SLD

Sheffield Resources Ltd.

August 25, 2006 09:30 ET

Sheffield Cuts Additional 267 Metres of Copper Mineralization at Moonlight Project

VANCOUVER, BRITISH COLUMBIA--(CCNMatthews - Aug. 25, 2006) - Sheffield Resources Ltd. ("Sheffield") (TSX VENTURE:SLD) continues its core drilling program designed to confirm the structural and ore control parameters at its Moonlight Project in Plumas County, California, and reports copper analyses of its fifth "HQ" diamond drill hole. Hole 06MN-5 was drilled at -57.3 degrees on an azimuth of 220 degrees. The hole was drilled southwesterly from the same collar location as holes 06MN-3 and 06MN-4. Hole 06MN-5 was directed to cross the southern boundary of the Placer Dome historical resource to check for mineralization to the south of the mineralization identified by the previous operator. Hole 06MN-5 intersected a total of 267 metres of copper mineralization in four zones and effectively flags the potential for substantial resource expansion to the south of the historical resource base at the Moonlight deposit.



DRILL RESULTS SUMMARY TABLE
--------------------------------------------------------------------
DRILL LENGTH FROM TO LENGTH Cu
HOLE metres metres metres metres (ft) %
--------------------------------------------------------------------
06MN-5 389 26 94 68m (223 ft) 0.44
--------------------------------------------------------------------
136 254 118m (387 ft) 0.45
--------------------------------------------------------------------
284 340 56m (184 ft) 0.34
--------------------------------------------------------------------
364 389 25m (82 ft) 0.32
--------------------------------------------------------------------


Hole 06MN-5 was drilled in a southwesterly direction from a collar located between historical drill holes ML-210 and ML-48 and passed close to the drill trace of ML-48 and below ML-301 and ML-18 all of which are vertical holes drilled in the 1960's by Placer. The 68 metres of 0.44% copper plus the 118 metres of 0.45% copper intersected by Sheffield's hole 06MN-5 between 26 and 254 metres in depth down the hole are believed to be geologically equivalent to the 256 metres of 0.50 intersected by Placer Dome Inc. in vertical hole ML-48. The third and fourth mineralized intervals in hole 06MN-5 occur below the rocks intersected in Placer drill holes ML-18 and ML-301 which holes did not intersect significant copper mineralization. Hole 06MN-5 ended in 0.32% copper mineralization, a grade that would be considered ore grade at many copper mines. Sheffield's geologists believe the extensive copper intersections in hole 06MN-5 that are located to the southwest of ML-48 clearly demonstrate the potential to find more copper to the south of Placer's historical resource.

David Jenkins, President of Sheffield Resources Ltd., comments, "While the economics of each mine or mineral deposit are to some extent unique, it is noteworthy that the 267 metres of copper mineralization intersected in 06MN-5 are essentially equal to or higher grade than the reserve average grade (0.33% copper at a 0.2% cut-off grade, including recoverable by-product credits) as reported in 2005 for one operating North American copper mine."



COMPARATIVE DRILL RESULTS FROM HISTORICAL DRILLING IN 1960's
---------------------------------------------------------------------
DRILL DEPTH FROM TO LENGTH Cu
HOLE metres metres metres metres (ft) %
---------------------------------------------------------------------
ML-210 136m (446 ft) 5m (16 ft) 125m (410 ft) 120m (394 ft) 0.44
---------------------------------------------------------------------
ML-48 470m (1541 ft) 54m (180 ft) 256m (840 ft) 201m (660 ft) 0.50
---------------------------------------------------------------------
287m (940 ft) 470m (1541 ft) 183m (601 ft) 0.30
---------------------------------------------------------------------


Sheffield holds a 100% interest in the Moonlight deposit subject to a 2% Net Smelter Return royalty (purchasable for US$500,000) on metals produced - by means of an option agreement on the 8 Diane Claims and by means of staking an additional 260 claims in the name of its operating subsidiary, American Sheffield Corp. Sheffield also holds the right to a 100% interest in the contiguous California-Engels Mining Company properties which were also extensively drilled by Placer.

Quality Control and Assurance

A rigorous Quality Control and Assurance program (QC/QA) is in place, including systematic inclusion of standard sample materials, blank samples, duplicate samples and inter-laboratory check assaying. Samples are sent in sealed containers to ALS Chemex in Reno, Nevada. ALS Chemex is a recognized ISO 9000 registered laboratory. The control samples and duplicate assay results received for the drilling program demonstrated to Sheffield Resources that the results are considered reliable. Copper is determined by atomic absorption spectrometry after a four acid digestion of a 0.4-gram aliquot. A second copper determination plus analyses of silver and other metals are made by ICP-AES after a three acid digestion of a 0.4-gram aliquot.

The exploration program is managed by Robert Wetzel, a California registered professional geologist and qualified person. The technical information in this news release has been prepared in accordance with Canadian regulatory requirements set out in National Instrument 43-101. David M Jenkins, P.Geo., and President of Sheffield Resources is designated the qualified person for the Moonlight Project.

About Sheffield Resources Ltd.

Sheffield Resources Ltd. is an exploration and development company focused on the acquisition and systematic exploration of advanced-stage copper projects with the goal of advancing them to development.

This news release may contain forward-looking statements including but not limited to comments regarding the timing and content of upcoming work programs, geological interpretations, receipt of property titles, potential mineral recover processes etc. Forward-looking statements address future events and conditions and therefore involve inherent risks and uncertainties. Actual results may differ materially from those currently anticipated in such statements. Sheffield Resources Ltd. relies upon litigation protection for forward-looking statements.

Contact Information