Silver Wheaton Corp. (TSX: SLW)(NYSE: SLW) ("Silver Wheaton" or the "Company") is pleased to announce that, further to our news release of December 20, 2007, Augusta Resource Corporation (TSX: AZC)(AMEX: AZC) ("Augusta") has elected to sell to Silver Wheaton 45% of the payable silver to be produced from its 100% owned Rosemont Copper Project ("Rosemont") for an upfront cash payment of US$165 million.

The upfront payment will be made on a drawdown basis to fund construction of the mine as milestones are achieved. Silver Wheaton will not be required to pay any further ongoing per ounce payments for silver delivered from Rosemont and is not required to fund or contribute to ongoing capital expenditures. Augusta will provide a completion guarantee with certain minimum production criteria by a certain date.

Both parties expect to complete the definitive agreement for this transaction by the end of June 2008. The transaction is subject to (a) Augusta receiving all necessary permits to construct and operate a mine in accordance with Augusta's 2007 Rosemont Feasibility Study, (b) Augusta having entered into committed arrangements for sufficient additional financing to construct and operate the mine, and (c) execution by the parties of definitive agreements on or before June 30, 2008, as well as receipt of any required regulatory approvals and third-party consents. Under the terms of the agreement, Augusta has the right to elect to increase the saleable amount of silver up to 90% of the life of mine payable silver, on substantially the same terms as above, at any time within three years from the execution of the definitive agreement.

The Rosemont Project is a copper-molybdenum-silver-gold porphyry deposit located in Pima County, Arizona. Based on a positive Feasibility Study released in August 2007, Augusta approved the project for development as a 75,000 tpd low cost open pit mine with a sulfide concentrator and SX/EW plant to treat sulfide and oxide mineral reserves. The proposed Rosemont mine is expected to produce annually an average of 220 million pounds of copper, 4.5 million pounds of molybdenum, 2.7 million ounces of silver and 15 thousand ounces of gold over the mine life, currently expected to be a minimum of 18 years.

Current proven and probable reserves at Rosemont contain 61.6 million ounces of silver, measured and indicated resources contain a further 4.9 million ounces and inferred resources contain 9.3 million ounces (please refer to our news release dated December 20, 2007 for a detailed explanation of Rosemont's current reserves and resources).