VANCOUVER, BRITISH COLUMBIA--(Marketwire - May 29, 2012) - Imperial Metals Corporation (News - Market indicators) reports a 73% increase in the Measured and Indicated resource estimate for its wholly owned Mount Polley open pit copper/gold mine located in central British Columbia.

The new Measured and Indicated resource estimate for Mount Polley is 361 million tonnes grading 0.284% copper, 0.297 g/t gold and 0.846 g/t silver. This is an increase of 73% over the Measured and Indicated resource estimate of 208.2 million tonnes of 0.317% copper and 0.291 g/t gold last reported in 2010 (ref: May 17/10).

Historically the Mount Polley resource did not include the estimated reserve. To conform to industry practice and to the other Imperial properties, the Company is reporting the Mount Polley resource estimate including the estimated reserve. The reserve is the economically minable part within the Measured and Indicated resource.

As disclosed in a prior news release (ref: Mar 30/12), the total Mount Polley reserve, which is now contained within the resource, is 87.3 million tones of 0.292% copper, 0.302 g/t gold and 0.407* g/t silver compared to 45.8 million tonnes of 0.306% copper, 0.262 g/t gold and 0.471 g/t silver at January 1, 2011. The reserve increase is a result of a complete re-evaluation of the Springer, Cariboo, C2 and WX deposits at Mount Polley, prompted by a combination of continuing exploration success and strong metal prices. This reserve estimate incorporates a single larger open pit⁽¹⁾ encompassing the Cariboo, C2, WX and Springer zones and extends the current mine life for Mount Polley from 2016 to the second quarter of 2023.

RESERVE/RESOURCE CALCULATION PARAMETERS

The parameters used in this updated resource are based on updated pit designs and the current Mount Polley production schedule. The ultimate pit designs were based on US$2.75 copper, US$1,250.00 gold, US$20.00 silver and US$0.95 exchange rate.

The economic mineral reserves and resources at Mount Polley mine were calculated as follows:

• A 3D block model was constructed using MineSight Mining Software.
• The property was zoned based on geological zones, the blocks and drill holes were then coded to reflect the zones.
• The drill holes were composited to 5 metre down the hole composites.
• Mineralized zones were identified within the geological zones, by kriging an indicator to identify the blocks that have a high probability of having greater than a 0.15% copper grade.
• The drill hole composites were then coded to match the indicator codes in the block model.
• Outlier grades were capped, and variograms for Cu, Au, Ag and Fe in each zone were generated.
• Grades were kriged into the block model, using zone and indicator matching.
• An oxide ratio number for each block was interpolated using an ID3 method, with zone and indicator matching. The oxide ratio number is used in the mill recovery formula.
• The mill recoverable grades were calculated using formulas based on historic recoveries as well as on and off site metallurgical test work.
• A dollar value was calculated for each block based on the metals prices, US/Can Exchange Rate, and mining, shipping and smelting costs.
• Lerchs-Grossman pit optimization software was used to identify economic pit shell based on the above economic parameters. Pit designs were created using the economic pit shells and design parameters from Golder Geotechnical Consultants of Vancouver.

Resource values were identified by summing all blocks that having a block grade greater than 0.25 copper equivalent. The copper equivalent was calculated using relative recovery and metal price for copper, gold and silver.

EqCu% = Copper% + Gold gpt / 1.510 + Silver gpt / 94.3

The resources were classified as inferred, indicated and measured based on the following three items; minimum number of drill holes used in the estimate, minimum number of composites, and the maximum distance to the nearest composite.

The ore reserves and resources were calculated and verified by Art Frye, Manager of Mining, Mount Polley Mining Corporation, and Greg Gillstrom, P. Eng., Geological Engineer, Imperial Metals Corporation, the designated Qualified Person as defined by National Instrument 43-101. Mr. Frye and Mr. Gillstrom have reviewed the contents of this release.

EXPLORATION UPDATE

The 2012 exploration drilling⁽¹⁾⁽²⁾ conducted to date has been focused below the north end of Springer pit, where the current model shows copper/gold mineralization continuing at depth below the 2023 pit design. The 2012 drilling, located within the Springer pit, drilled through about 100 to 200 metres within the current 2023 mine plan. All 17 Springer drill holes totalling 7,976 metres have encountered significant copper/gold mineralization to depths in excess of 450 metres below the proposed pit. Drill holes SD12-111 to SD12-119 (partial) are included in the resource update. Additional drill results beyond SD12-119 will continue to increase the tonnage and confidence level of future resource calculations. Silver analysis has not yet been completed for any of the intervals reported.

The mineralization encountered is characterized by very fine disseminated copper sulphides (chalcopyrite and bornite) in a classic alkalic porphyry environment. Intense potassic alteration obscures the protolith texture and identity, similar to other mineralized areas at Springer zone. Mineralization is relatively continuous, but is occasionally cut by barren post-mineral dykes. In the mineralized intercepts, gold grades in grams per tonne are about the same as the copper grade in percent.

Selected significant intercepts from the Springer zone⁽³⁾:

Exploration drilling continues at Mount Polley with two surface diamond drills, and over the summer season field crews will work on new and existing prospects by geologic mapping, prospecting, trenching, ground magnetometer surveying and geochemical sampling in an effort to generate new targets.

In addition, underground development continues at the Boundary zone with 286 metres of ramp and cross-cuts completed from January to April this year. Mount Polley plans to develop and mine one of the numerous mineralized breccia bodies that comprise this zone to determine the best mining method.

Steve Robertson, P.Geo., the designated Qualified Person as defined by National Instrument 43-101 for the exploration programs, has reviewed this news release. Mount Polley samples for the diamond drilling reported were analyzed at the Mount Polley mine laboratory and at Acme Analytical Laboratories in Vancouver. A full QA/QC program using blanks, standards and duplicates was maintained for all diamond drilling samples submitted to the labs. The porphyry and breccia related mineralized areas at Mount Polley are irregular in shape and true thicknesses have not been estimated.

Imperial is a mine development and operating company based in Vancouver, British Columbia. The Company's key properties are two open pit mines: Mount Polley copper/gold mine and Huckleberry copper/molybdenum mine, both in British Columbia, as well as development stage Red Chris copper/gold property in British Columbia and Sterling gold property in Nevada.

Documents available on www.imperialmetals.com:

⁽¹⁾ Springer pit drill plan;

⁽²⁾ Springer pit vertical section;

⁽³⁾ Springer pit assay results

CAUTIONARY NOTE REGARDING "FORWARD-LOOKING INFORMATION":

THIS NEWS RELEASE CONTAINS "FORWARD-LOOKING STATEMENTS" WITHIN THE MEANING OF CANADIAN AND UNITED STATES SECURITIES LAWS. EXCEPT FOR STATEMENTS OF FACT RELATING TO THE COMPANY, CERTAIN INFORMATION CONTAINED HEREIN CONSTITUTES FORWARD-LOOKING STATEMENTS.

WHEN WE DISCUSS CURRENT AND FUTURE EXPLORATION PROGRAMS, EXPLORATION RESULTS, AND EXPECTATIONS OR ASSUMPTIONS BASED ON THOSE RESULTS, WE ARE MAKING STATEMENTS CONSIDERED TO BE FORWARD-LOOKING INFORMATION OR FORWARD-LOOKING STATEMENTS UNDER CANADIAN AND UNITED STATES SECURITIES LAWS. WE REFER TO THEM IN THIS NEWS RELEASE AS FORWARD-LOOKING INFORMATION. THE FORWARD-LOOKING INFORMATION IN THIS NEWS RELEASE TYPICALLY INCLUDES WORDS AND PHRASES ABOUT THE FUTURE, SUCH AS: PLAN, EXPECT, FORECAST, INTEND, ANTICIPATE, ESTIMATE, BUDGET, SCHEDULED, BELIEVE, MAY, COULD, WOULD, MIGHT AND WILL.

WE CAN GIVE NO ASSURANCE THAT THE FORWARD-LOOKING INFORMATION WILL PROVE TO BE ACCURATE. IT IS BASED ON A NUMBER OF ASSUMPTIONS MANAGEMENT BELIEVES TO BE REASONABLE, INCLUDING BUT NOT LIMITED TO: THE CONTINUED OPERATION OF THE COMPANY'S MINING OPERATIONS, THAT THE MINING OPERATIONS WILL OPERATE AND THE MINING PROJECTS WILL BE COMPLETED IN ACCORDANCE WITH THEIR ESTIMATES AND ACHIEVE STATED PRODUCTION OUTCOMES, AND SUCH OTHER ASSUMPTIONS AND FACTORS AS SET OUT HEREIN. IT IS ALSO SUBJECT TO RISKS ASSOCIATED WITH OUR BUSINESS, INCLUDING BUT NOT LIMITED TO: RISKS INHERENT IN THE MINING AND METALS BUSINESS; COMMODITY PRICE FLUCTUATIONS AND HEDGING; COMPETITION FOR MINING PROPERTIES; SALE OF PRODUCTS AND FUTURE MARKET ACCESS; MINERAL RESERVES AND RECOVERY ESTIMATES; CURRENCY FLUCTUATIONS; INTEREST RATE RISK; FINANCING RISKS; ENVIRONMENTAL RISKS; FOREIGN ACTIVITIES; LEGAL PROCEEDINGS; AND OTHER RISKS THAT ARE SET OUT IN OUR ANNUAL INFORMATION FORM AND MANAGEMENT'S DISCUSSION & ANALYSIS. IF OUR ASSUMPTIONS PROVE TO BE INCORRECT OR RISKS MATERIALIZE, OUR ACTUAL RESULTS AND EVENTS MAY VARY MATERIALLY FROM WHAT WE CURRENTLY EXPECT AS SET OUT IN THIS NEWS RELEASE.

WE RECOMMEND YOU REVIEW OUR ANNUAL INFORMATION FORM AND ANNUAL MANAGEMENT'S DISCUSSION AND ANALYSIS, WHICH INCLUDE A DISCUSSION OF MATERIAL RISKS THAT COULD CAUSE ACTUAL RESULTS TO DIFFER MATERIALLY FROM OUR CURRENT EXPECTATIONS. FORWARD-LOOKING INFORMATION IS DESIGNED TO HELP YOU UNDERSTAND MANAGEMENT'S CURRENT VIEWS OF OUR NEAR AND LONGER TIME PROSPECTS, AND IT MAY NOT BE APPROPRIATE FOR OTHER PURPOSES. WE WILL NOT NECESSARILY UPDATE THIS INFORMATION UNLESS WE ARE REQUIRED TO BY SECURITIES LAWS.