Toronto-based HudBay Minerals Inc. says it will make a bid worth nearly $500 million for all of the shares of Augusta Resource Corp., which is vying to build the Rosemont Mine in the Santa Rita Mountains southeast of Tucson.

HudBay, which already owns about 16 percent of Toronto-based Augusta, said Augusta shareholders would each get about a third of one HudBay share for each Augusta common share. The offer represents an 18 percent premium over Augusta’s closing price on Friday, for a total offer value of $540 million Canadian or about $490 million U.S., HudBay said.

Augusta said in a news release today that its board of directors will meet this week to discuss HudBay’s offer, and that the company will update its shareholders following that board meeting.

Augusta’s shares closed at $2.95, up nearly 30 percent from Friday’s close, in trading on the New York Stock Exchange.

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