Sheffield Resources Begins Diamond Drilling On The Moonlight Copper Project.

VANCOUVER, British Columbia -- Sheffield Resources Ltd.'s (TSX VENTURE:SLD) plan of operation submitted by the company, on October 8, 2005, for its proposed 2,000-metre HQ-gauge diamond drill program at its Moonlight project in Plumas county, California, was approved by the United States Department of Agriculture (USDA) Forest Service on December 2, 2005.

Operations under the approved plan of operation commenced the morning of December 3, 2005, with construction of the first drill pad. Kirkness Diamond Drilling Co. Inc. of Carson, Nevada, mobilized a diamond drill and crew, and drilling commenced on December 6, 2005.

The drill program will be the first drilling of angle holes on the property and is designed to provide additional structural information about the mineralization occurring on the property. Previous exploration of the Moonlight deposit by Placer Dome Inc. included 199 vertical diamond drill holes and reverse circulation holes totaling 99,436 lineal feet.

The company holds the Moonlight property by means of an option agreement on the eight Diane claims and by means of 82 claims acquired by staking in the name of its operating subsidiary American Sheffield Corp. The agreement allows the company to earn a 100-per-cent interest in the claims subject to a 2-per-cent net smelter return (NSR) royalty on metals produced from the claims or other claims held by the company within five kilometres of the claims. The NSR royalty is purchasable for $500,000 (U.S.). Gems and industrial minerals produced from the claims are subject to a 5-per-cent gross overriding royalty (GORR).

The claims are located in Plumas County, California. They are within 15 miles by high-speed logging access road of highways, rail transportation and electrical power. A number of small resource-based communities in the region are potential sources of trained labour.

According to a report written to the standards of National Instrument 43-101 by George Cavey, PGeo, the Moonlight project is based on porphyry copper-type mineralization hosted by the Lights Creek stock. At least three zones of copper mineralization have been identified in the district by past workers, including most recently the U.S. subsidiary of Placer Development Ltd. (now Placer Dome Inc.). The primary copper-bearing minerals occurring in the Moonlight deposit are bornite and chalcopyrite with lesser amounts of covellite and chalcocite. Gold, silver and molybdenum are known to be present in the Moonlight deposit, but as was common during the 1960s these metals were not systematically assayed for during resource delineation drilling.

The subsidiary of Placer Dome, during its tenure at the Moonlight project, estimated the tons and grade of mineralized material in the Moonlight deposit several times. The estimates for only the Moonlight deposit ranged from 180 million tons at an average copper grade of 0.39 per cent (above a 0.23-per-cent copper cut-off grade) to 171 million tons at an average copper grade of 0.315 per cent (above a 0.25-per-cent copper cut-off grade). The author of the latter study noted that his estimates did not adequately reflect the near-vertical localized controls to the mineralization and recommended further testing with angled holes. Both estimates were classified by Placer's staff as either minable reserves or ore reserves, respectively, at that time they were issued. These estimates are historical and while important to an understanding of the property potentials they are not reserves under the CIM protocols required by National Instrument 43-101 as they predate the establishment of said protocols. The reader is cautioned as follows:

--the issuer has not done the work necessary to verify the classification of the resource or reserve,

--the issuer is not treating them as an NI 43-101-defined resource or reserve verified by a qualified person; and

--the historical estimate should not be relied upon.

Both the metal grades and the total number of tons of mineralized geological materials can likely be substantially enhanced by drilling properly oriented large-diameter core holes with modern wireline drilling techniques to depths below and along strike of the copper deposit drilled by Placer Dome.

Structure appears to play a significant role in the controls to the better-grade copper mineralization at the Moonlight deposit. Various workers have noted the existence of near-vertical, well-mineralized veins that may contain significant as-yet-underdetermined concentrations of copper mineralization. All of the 199 diamond drill holes, totaling 99,436 lineal feet, at the Moonlight deposit were vertical and so would be unlikely to properly test a near-vertical mineralizing system. Therefore, the importance of these steeply dipping mineralized systems to the overall grade and tonnage at the Moonlight deposit will not be known until angled holes are drilled throughout the Moonlight deposit.

Previous drilling of the deposit was completed using small-diameter BX-gauge equipment and standard drilling techniques, which are not in practice as efficient in recovery of friable-vein-hosted sulphide minerals as modern wireline drilling techniques. During the early phases of drilling, Placer Dome completed parallel core and sludge analyses of selected intervals in seven drill holes in the Moonlight deposit. Six of the seven holes returned sludge assay results that averaged a 48-per-cent increase compared with the core assays, only one of the holes returned sludge results that were lower than the corresponding core assay results. Although no final conclusions can be developed from these results, a preliminary conclusion is that the reported copper grade of the Moonlight deposit may be understated.

Drill holes at the Moonlight deposit commonly terminated at a depth of approximately 500 feet and within the copper zone the holes most commonly ended in mineralization. A very few substantially deeper holes were drilled to as much as 1,700 feet of depth. These deeper drill holes indicated copper mineralization, of similar grade and character as that mineralization for which Placer Dome estimated ore reserves, extends to at least that depth.

The Moonlight project is based on a porphyry copper deposit that has been extensively drilled and compares favourably with other deposits that are in advanced exploration or have been in production. The project is believed by management to have substantial potential to yield materially enhanced copper grades and substantial increases in tonnage to a program of oriented drill holes using modern drilling techniques. The project cost structure can be expected to benefit from its location in close proximity to electrical power, rail transport and a skilled resource-oriented labour force.

Robert Wetzel, registered geologist (California) is managing the exploration program on the Moonlight project. David Jenkins, P.Geo (B.C.), is the company's project supervisor and qualified person for the purposes of NI 43-101 Standards of Disclosure for mineral projects for the Moonlight project.