Sherwood Copper Corporation

Sherwood Copper Corporation

June 27, 2005 08:30 ET

Sherwood Reports Increased Resources at Minto Project, Yukon; More Tons at Higher Grades than Previously Estimated

VANCOUVER, BRITISH COLUMBIA--(CCNMatthews - June 27, 2005) - Sherwood Mining Corporation (TSX VENTURE:SWM) is pleased to announce the results of an independent, National Instrument 43-101 resource estimate prepared for the Minto Project in the Yukon. This new estimate incorporated the results of holes drilled subsequent to the 1994 estimate and resulted in an approximately 10% gain in contained copper and gold.

"We are very pleased with these results, which show the Minto project to be even more robust than previously thought," said Bruce McLeod, Sherwood's President & CEO. "It is also encouraging to see that more than 90% of the current resources are classified in the measured and indicated categories, and are therefore suitable for inclusion in a feasibility study."

Minto Resource Estimate

Mineral resources for the Minto project were estimated based on approximately 239 drill holes, including 11 holes drilled in 2001. The following table sets out the mineral resource for the Minto Project.

Average Grade
Mineral Resource Cutoff Tons ---------------------------
Category (Cu %) (000's) Cu (%) Au (oz/t) Ag (oz/t)
Measured 0.5 3,970 1.74 0.013 0.215
Indicated 0.5 5,220 1.90 0.019 0.245
------ ------ --------- ---------
Measured + Indicated 0.5 9,190 1.83 0.016 0.232
Additional Inferred 0.5 770 1.41 0.013 0.175

The total contained metal in the measured and indicated estimate is 336 million pounds of copper, 147,000 oz of gold and 2.1 million oz of silver, versus 310 million pounds of copper, 133,000 oz of gold and 2.0 million oz of silver estimated in 1994. The new additional inferred resource contains is 22 million pounds of copper, 10,000 oz of gold and 0.1 million oz of silver, versus 5 million pounds of copper, 2,000 oz of gold and negligible silver estimated in 1994.

This new resource estimate compares to approximately 8.78 million tons grading 1.76% copper, 0.015oz/t gold and 0.223oz/t silver in the measured and indicated category in 1994, and 314,000 tons grading 0.85% copper, 0.006oz/t gold and 0.090oz/ton silver in the inferred category in 1994.

Resource Estimation Methodology

The mineral resources for the Minto Project were estimated by Giroux Consulting. Gary Giroux, P.Eng. is the Qualified Person under National Instrument 43-101 responsible for the estimate. A Technical Report is being prepared by Orequest Consultants and will be filed within 30 days on SEDAR and may be accessed at

Mineralization was interpreted in seven zones and statistical analysis for each metal run for each zone. Assays were them composited for 10 foot intervals and statistical analysis run for each metal and variography estimated for each mineralized domain. This geostatistical analysis was used to construct a block model, with individual blocks 25 feet by 25 feet by 10 feet high. A tonnage factor for each block was established, as in 1994, based on the kriged grade of copper. The basis for this interpretation came from an Asarco feasibility study completed in 1976. Ordinary kriging was used to interpolate grades for copper, gold and silver into the block model. Blocks were then classified into measured, indicated and inferred based on search ellipses dimensions tied to semivariogram ranges combined with a relative-kriging standard deviation (RKSD) calculated for each block.

The results were presented as grade-tonnage tables for a wide variety of copper cut-off grades to show how sensitive tonnage is to increasing grade. These will be detailed in the technical report to be filed on SEDAR. A current economic cutoff for this property has not been established; the 0.5% copper cut-off has been reported here to allow direct comparison to the previously disclosed historic resource estimates.

It should be noted that the block model was capped at an elevation of 2590 feet to allow direct comparison to prior estimates, where a similar elevation cap was used because of an assumed level of oxidation at the shallower levels. However, it is recommended that future estimates not incorporate this elevation cap and oxidation levels be determined by assay rather than assumed.

Mineral resources that are not mineral reserves do not have demonstrated economic viability. Mineral resource estimates do not account for mineability, selectivity, mining loss and dilution. These mineral resource estimates include inferred mineral resources that are normally considered too speculative geologically to have economic considerations applied to them that would enable them to be categorized as mineral reserves. There is also no certainty that these inferred resources will be converted to measured and indicated categories through further drilling, or into mineral reserves once economic considerations are applied.

Historical Data & Verification

The estimate is based upon drill programs completed by several different companies between 1971 and 2001 that total 368 drill holes and 161,809 feet drilled. Of this total, 139 holes (72,650 feet) were completed by companies in joint venture with ASARCO in 1971-1974; 182 holes (70,229 feet) were drilled by companies associated with Falconbridge in 1973-74, 1984 and 1989; and 47 holes (18,930 feet) were drilled by Minto Explorations in 1993-96, 1999 and 2001. Of these drill holes, 239 holes lie within the limits of the resource estimate, while the others are exploration holes on other portions of the Minto property.

The sampling done in these drill programs were carried out by major, international mining companies, however no detailed reports of sample methods, analyses, quality control measures or security procedures are available for verification. Available information indicates that core was mechanically split and half sent for analyses. Because of the consistent, disseminated nature of the mineralization, no inadvertent biasing of results is expected. During the 1970's, most samples were sent to Chemex Labs in Vancouver for analysis. At that time, copper analyses were done by digesting a 2gram sample in perchloric and nitric acid with an AA finish. Modern copper analysis tends to use a 0.4gram sample ground to 150 mesh and aqua regia digestion. Some of the early samples were not analyzed for gold. Bondar-Clegg of Vancouver carried out the analysis of the 2001 samples. Each sample was crushed to -10 mesh from which a 250gram slit was separated and crushed to -150mesh. For analysis, a 0.25gram sample was digested with hydrochloric, nitric, HCL04 (??) and hydrofluoric acids with final copper determination by AA spectroscopy. Gold and silver were determined by fire assay using a 30gram sample and AA finish.

No independent verification has been carried out on this data. The work on the Minto property has been carried out by reputable companies and there is no reason to question the veracity of the information. ASARCO drilled five verification holes in 2001 to confirm grades and intervals of the main zone of the Minto deposit. The confirmation drilling shows that both the copper and gold grades and thicknesses in the mineralized zones are generally higher than indicated by the original drill results. Sherwood intends to complete its own verification drilling within the limits of the deposit during the summer of 2005.

Minto Project & Plans

Sherwood's successful consolidation of the ownership of the Minto Project provides a unique investment opportunity - participation in an already permitted, partially constructed, high grade, open pit copper project located in Canada with infrastructure and exploration potential on the property.

Sherwood plans to commence a 10,000-12,000m drill program at the Minto Project in July 2005 with three objectives: (1) limited confirmatory drilling within the previously defined pit limits to evaluate the possible historic underestimation of gold grades, (2) upgrade the estimated 8% of the resource within the previously defined pit from inferred to indicated category to allow its inclusion in a feasibility study, and (3) step out drilling on the margins of the existing resource with the aim of increasing the total resource, with a particular emphasis on the higher grade trends. On completion of this program, Sherwood plans to update the resource estimate and complete a new feasibility study by the end of 2005.

Additional details on the Minto Project and the acquisition of Minto Explorations are detailed in Sherwood's offer to purchase and takeover bid circular dated April 29, 2005 which is available on Minto Explorations' profile on the SEDAR website at

Cautionary Statement

This news release contains certain forward looking statements and you are referred to Sherwood' Annual Report, Annual Information Form and recent press releases in respect of Minto Explorations, the Minto Project and the acquisition thereof for a discussion of the risks associated with forward looking statements and other risk factors.

All resource estimates reported in this press release are calculated in accordance with the Canadian National Instrument 43-101 and the Canadian Institute of Mining and Metallurgy Classification system. These standards differ significantly from the requirements of the United States Securities and Exchange Commission, which permits U.S. mining companies in their SEC filings to disclose only those mineral deposits that qualify as proven or probable "reserves" because a determination has been made based on an appropriate feasibility study that the deposits could be economically and legally extracted or produced. Accordingly, resource information reported in this disclosure may not be comparable to similar information reported by United States companies. The term "resource(s)" does not equate to "reserves" and normally may not be included in documents filed with the Securities and Exchange Commission, and investors are cautioned not to assume that "resources" will be converted into "reserves" in the future.

This disclosure uses the term "inferred resources". While this term is recognized by Canadian regulations concerning disclosures by mining companies, the U.S. Securities and Exchange Commission does not recognize it. "Inferred resources" have a great amount of uncertainty as to their existence and as to their economic and legal feasibility. It cannot be assumed that all or any part of the "inferred resources" will ever be upgraded to a high category. Under Canadian rules, estimates of "inferred resources" may not form the basis of feasibility or pre-feasibility studies except in rare cases. Investors are cautioned not to assume that part or all of an "inferred resource" exist or are economically or legally feasible.


D. Bruce McLeod, P.Eng., President

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

Contact Information

  • Sherwood Mining Corporation
    Bruce McLeod
    President of Sherwood
    (604) 687-7545 or (888) 338-2200
    (604) 689-5041 (FAX)