Sheffield Resources Ltd.

Sheffield Resources Ltd.

April 24, 2008 15:00 ET

Sheffield Resources Ltd. Enters Into Agreement With Nevoro Inc.

VANCOUVER, BRITISH COLUMBIA--(Marketwire - April 24, 2008) - Sheffield Resources Ltd. ("Sheffield") (TSX VENTURE:SLD)(FRANKFURT:S2Q) and Nevoro Inc. ("Nevoro") (TSX:NVR) have entered into an agreement pursuant to which Nevoro will acquire 100 per cent of the common shares of Sheffield. According to the agreement, Nevoro will issue 0.8 shares for each Sheffield share, which represents a value of approximately C$0.48 per share based upon the closing price of Nevoro common shares on the Toronto Stock Exchange on April 23, 2008.

Terms of the Acquisition

The transaction is subject to a number of conditions precedent including: (a) Sheffield receiving a positive fairness opinion, (b) shareholder approval and (c) regulatory approvals. Sheffield's Board of Directors has received a fairness opinion to the effect that consideration to be received by Sheffield shareholders is fair from a financial point of view and the Board will recommend the transaction to Sheffield's shareholders. Shareholder approval for the transaction will be sought at a special shareholders' meeting or in conjunction with Sheffield's AGM on a specific date yet to be determined. The final structure of the transaction will be determined on the basis of tax, security and corporate law advice in order to insure the most efficient structure of each of the parties and their respective shareholders. Details of the final structure will be announced when available.

According to the agreement, each Sheffield common share will be cancelled and the holders thereof will receive for each share 0.80 of one Nevoro common share, which represents a value of approximately C$0.48 per share based upon the closing price of Nevoro common shares on the Toronto Stock Exchange on April 23, 2008. Holders of common share purchase warrants of Sheffield, in accordance with the terms of such warrants, in lieu of Sheffield's shares, shall receive upon the subsequent exercise of such holder's Sheffield Warrant, 0.80 of one Nevoro Share. Each holder of an outstanding Sheffield stock option, in accordance with the terms of the Sheffield stock option ("Sheffield Option") plan, shall receive an option to acquire the number of Nevoro Shares equal to the product of: (i) the number of Sheffield Shares subject to the Sheffield Option immediately before the closing, and (ii) 0.80 of one Nevoro Share, the exercise price per Nevoro Share shall be an amount equal to the quotient of (A) the exercise price per Nevoro Share subject to such Sheffield Option immediately before closing divided by (B) 0.80.

Currently, Nevoro has 75,163,585 common shares outstanding and Sheffield has 35,422,497 shares issued and outstanding. Nevoro announced on April 17, 2008 a plan of arrangement to acquire 100% of Aurora Metals (BVI) Limited ("Aurora") (OTCBB:AURMF) 19,981,476 issued and outstanding shares at an exchange ratio of 1 for 1 share. Upon the closing of both acquisitions Nevoro, will have 123,483,058 issued and outstanding common shares and Nevoro's current shareholders will hold approximately 60.9%, Sheffield shareholders will hold approximately 22.9% of these shares, and Aurora shareholders will hold 16.2%

On a fully diluted basis, there will be 148,525,022 shares outstanding with current Nevoro shareholder having approximately 59%, Aurora shareholders having approximately 13.4% and Sheffield shareholder having approximately 27.6%. Exercise of all of the outstanding warrants and options in each company will raise an additional $11.2 million in cash.

In addition to the agreement, Nevoro and Sheffield have agreed to a working capital funding to Sheffield by Nevoro by way of a secured grid promissory note (the "Grid Note") under which Sheffield can receive advances up to C$400,000, in the aggregate, from Nevoro. The advances will be secured by a mortgage of Sheffield's interest in the Moonlight Copper Project in Plumas County, California and are subject to an interest rate equal to the Prime Rate, as quoted by the Royal Bank of Canada, plus 2% per annum. The Note can be called on 90 days notice, by Nevoro and can be satisfied, at Sheffield's option, by the issuance of common shares of based on a conversion rate equal to the lower of: (i) 75% of the average closing price of Sheffield's common shares as listed on the Toronto Stock Exchange - Venture Exchange (the "TSX-V") for the 20 trading days immediately preceding the date of this Agreement; and (ii) 75% of the average closing price of Sheffield's common shares as listed on the TSX-V for the 20 trading days immediately preceding the effective date of conversion (being the 90th day after the date of demand), and subject to the acceptance of the TSX-V to these terms of conversion.

Sheffield's Board believes this transaction will materially contribute to the timely development of the Moonlight Project. Nevoro has the funds in hand, should the Nevoro Board chose to use them, to complete the work programs Sheffield planned for 2008 which could lead to a near term prefeasibility study. The Nevoro Board is populated with professionals that individually have long histories of providing exceptional shareholder value and have in the very recent past raised very large sums of money for each of a number of programs.

About Nevoro Inc.

Nevoro is a TSX-listed exploration and development company focused on the discovery of base and precious metals in the western USA. Nevoro holds 13 gold projects in Nevada and Idaho. Nevoro's principal asset is the St. Elmo gold-silver project to which it expects to add the Stillwater project of Aurora and Sheffield's Moonlight and Golden Loon projects.

Nevoro announced in a news release, dated April 17, 2008, it had entered into an arrangement agreement to acquire pursuant to a court-approved plan of arrangement the 19,981,476 issued and outstanding shares of Aurora Metals BVI Limited ("Aurora") (OTCBB:AURMF) at an exchange ratio of one Nevoro share per one Aurora share. Upon closing of the Aurora and Sheffield acquisitions Nevoro will as a consequence have 130,317,557 shares issued and outstanding. The Nevoro acquisition of Aurora is expected to close by July 31, 2008 and is subject to a number of conditions precedent that are described in a Nevoro press release.

St. Elmo Mine Project

Situated in northeastern Nevada, St. Elmo is a district-scale exploration play located at the intersection of the Midas Trough structural zone and a series of northwest-trending faults in Elko County, Nevada. The Midas Trough hosts several established gold mines including the Ivanhoe, Ken Snyder, Jerritt Canyon mines as well as the past-producing mines of the Island Mountain district and the Jarbidge district. These operations have total reserves in excess of 13 million ounces.

The 415 claims (343 staked by Nevoro, 72 leased) comprising the 8,500 acre St. Elmo project host a number of small, past-producing operations including the St. Elmo gold mine, the Rosebud silver-lead-zinc mine, the Diamond Jim silver-lead-zinc mine and the Gribble antimony mine. The property includes in addition a number of old mines/prospects with high-grade values of up to 3 oz/ton gold, 30 to 50 oz/ton silver as well as significant tungsten, antimony and molybdenum occurrences. This is a large under-explored area with considerable upside for epithermal gold-silver, antimony-tungsten-molybdenum, gold, silver skarn, or large tonnage disseminated precious metal deposits.

The St. Elmo mine is an epithermal vein system hosted in a 2.9 km long, fault zone and reportedly produced high-grade gold in the 1940s. A 1500 ton bulk sample extracted by Hazen Research ("Hazen") of Denver, Colorado reportedly averaged 11.3 g/t (0.33 oz/ton). A bulk sample weighing 360 kg reportedly averaged 80.9 g/t (2.36 oz/ton) was tested by Hazen, who reported 95.0 per cent of the gold could be recovered using standard gravity and flotation methods. In 1999, reconnaissance drilling (3 diamond drill holes) under the St. Elmo workings intersected values of up to 16 grams per tonne gold (0.466 oz/ton gold) over 2 metres within a 16 metre wide zone of quartz breccia.

The Diamond Jim mine and Rosebud mines have potential for large, low-grade, silver-base metal mineralization, there is also the potential for structural and stratigraphically controlled gold deposits. Outcrop within steeply dipping structures east of the Diamond Jim assayed 0.4 oz/ton gold and jasperoid outcrops associated with low angle structures assayed 7 g/t gold (0.2 oz/ton gold) -- the area remains unexplored. Values of up to 5 g/t gold have been recovered in the rocks above the Rosebud mine. Eleven holes, each approximately 100 m in length, were drilled during 1962 to test the down-dip extension of the Rosebud mine. Each hole reportedly intersected an average of 12 to 150 oz/ton silver over widths of 2.5 to 3.0 m. Additionally, three holes drilled east of the Rosebud mine are reported to have intersected from 30 to 50 oz/ton silver. These drill intersections apparently never received further follow-up investigation.

Two newly discovered parallel vein systems have been found east of the St. Elmo vein. The Sinter vein structure is at least 500 metres long and the Barite vein is at least 300 m long. Each structure is associated with a siliceous alteration zones within limestone and locally contain barite. Mapping and sampling are underway and evidence suggests these vein structures could represent a possible hot spring gold system, the model for which would be the McLaughlin mine in California with reserves of 2.5 million ounces gold and the Ivanhoe project with reserves and resources of 1.5 million ounces gold.

Nevoro has established nine target areas that host both high-grade vein and bulk-tonnage targets, many of which are ready for drilling. These targets include 1) the St. Elmo vein zone comprising several anastimosing gold- and silver-bearing quartz veins and breccia zones with a strike length in excess of 2000 m (6,600 feet); and 2) the Diamond Jim Mine area with mineralized low-angle thrust faults which intersect high-angle veins and structures. In addition to these targets, the project has the potential to host Carlin-style, sediment-hosted gold deposits, as well as tungsten, molybdenum and gold skarn deposits.

The Stillwater Project, consisting of almost 1,853 hectares (4,578 acres) of patented and unpatented claims, is located approximately 80 mi (129 km) west-southwest of Billings, Montana. The tenures are for the most part contiguous with ground held by the Stillwater Mining Company ("SMC") which operates on the SMC tenures the world class Stillwater and East Boulder Mines. The Stillwater Mine produces approximately 124,000 ounces of platinum and 413,000 ounces of palladium per year from the J-M Reef and is considered the world's highest-grade and third largest PGM producing operation.

The Stillwater project is underlain by the Stillwater complex, an Archean layered mafic-ultramafic magmatic intrusive body. The body is exposed over 47 kilometres by eight kilometres and is tilted on edge, but otherwise similar to the Bushveld complex of South Africa. Both the Stillwater and Bushveld rocks contain significant layers (stratiform) platinum group metals, Ni-Cu-Co and Cr deposits.

Aurora's claim block covers portions of a 17 km strike length in the ultramafic series and basal series rocks which lie underneath the lower banded series rocks, which are host to the Stillwater Mine, and more than 12 km of strike length of the Basal Series rocks, which are host to potentially commercial Ni-Cu-Co deposits. The geology of these deposits is very similar to that of the Bushveld Complex in South Africa, but in contrast is characterized by platinum group metals ("PGM") reefs typically richer and thicker than those of the Bushveld. Aurora's Stillwater project consists of a number of significant Ni-Cu-Co and chromitite deposits with historical but not NI 43-101 compliant resources. In the event that Nevoro's contemplated exploration confirms the historical resources previously estimated by major mining companies and the United States Geological Survey these prospects will likely be classed as advanced-stage to pre-development stage due to the substantial historic databases. Equally important are several promising, largely untested PGM targets with upside potential perhaps comparable to the J-M Reef.

Among the several well studied base metal and PGM deposits on the property are the Mouat Ni-Cu-Co prospect, Nye Basin Ni-Cu-Co+/-PGM prospect and Benbow Mine area. The Mouat Ni-Cu prospect was extensively drilled by Anaconda for nickel and copper, but remains largely untested for PGMs. Anaconda's published (1987) historical resource estimates for the Mouat is 92 million tons grading 0.27% Ni and 0.29% Cu using a 0.20% Ni cut-off grade or 23 million tons grading 0.62% Ni and 0.45% Cu using a 0.4% Ni cut-off. These are historical resource estimates and while they are estimates by a major mining company, a qualified person has not done sufficient work to classify the historical estimate as current mineral resources, the issuer is not treating the historical estimate as current mineral resources and the historical resource estimate should not be relied upon.

In addition, based on historical drilling the United States Geological Survey ("USGS") in 1987 estimated the Nye Basin area may contain in the range of 70 million to 90 million tons grading between 0.6 and 0.8 per cent Ni and 0.6 to 0.8 per cent Cu. The USGS also estimated the Benbow area may contain between 10 million and 20 million tons at 0.4 per cent to 0.5 per cent Ni and 0.5 per cent to 0.6 per cent Cu. Both of the USGS estimates are conceptual exploration targets and are not historical resources or NI 43-101 compliant resources. The potential quantity and grade of the USGS estimates are conceptual in nature and there has been insufficient exploration to define a mineral resource. It is uncertain if further exploration will result in discovery of a mineral resource.

In addition to base metal prospects there are chromitite and PGM prospects on the Nevoro tenures including the Mouat/Mountain View mine chrome deposits and the "A" and "B" chromitite zones. The "A" and "B" chromitite zones are the lowest of a series of seven chromitite zones and at current high metal prices are of interest for their chrome content as well as their enriched PGM content. Some of the higher seams were mined for their chromium content and are part of the Mouat/Mountain View mine which is one of largest (if not the largest) known chrome deposits in North America. The Mountain View mine was reportedly closed with 15 years of reserves remaining unmined. The "A" and "B" chromitite prospects are located in the Crescent Creek and Nye Basin areas of the property which are located across the Stillwater River from the mineralization at Mouat/Mountain View.

About Sheffield Resources Ltd.

Sheffield Resources Ltd. is an exploration and development company focused on the acquisition and systematic development of copper and nickel/cobalt deposits with potential for large tonnages of ore that are located close to infrastructure in politically stable areas.

David Jenkins, P.Geo., President of Sheffield is the qualified person who is responsible for the technical content of this press release.

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

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