HudBay Minerals Inc. will acquire the remainder of Augusta Resource Corp. with a sweetened offer of $405 million, the Augusta Resources announced in June 24 statement.

HudBay Minerals already owns 16 percent of Augusta and will acquire the rest with an offer of 0.17 of a warrant to acquire one of its shares for each Augusta share, in addition to its original offer of 0.315 of a share. The revised bid is valued at about C$3.56 a share. That is about 10 percent more than the value of a previous offer from HudBay, Bloomberg reported. 

The gem of the acquisition of is Augusta’s Rosemont copper project, south of Tucson, AZ. The Rosemont project is expected to produce 243 million lbs. of copper per year, according to its 2012 feasibility study, which could account for as much as 10 percent of United States copper output, making Rosemont the third largest copper mine in the United States.

In addition to copper, Rosemont is expected to produce significant amounts of silver and molybdenum over its more than 21 year mine life. As of July 2012, Rosemont has proven and probable reserves of 5.9 billion lbs of copper and 194 million lbs of molybdenum and inferred sulfide mineral resources of 1.1 billion lbs of copper and 35 million lbs of molybdenum. Production is projected to commence in the first quarter of 2017.

Augusta, based in Vancouver, had rejected HudBay’s previous offer as too low and opportunistically timed, saying it expected permits to develop Rosemont would be issued soon and boost its shares. Augusta ran a process to solicit higher bids and said in April it signed agreements to exchange confidential information with 10 groups, but didn’t announce any alternate transaction to HudBay’s offer.

“After a thorough process to consider all of our alternatives, we are pleased to have agreed on a mutually beneficial transaction representing a successful conclusion to our value maximizing process,” Augusta chairman Richard Warke said in the statement.

HudBay also has a right to match any alternative deal proposed by another party and will receive a fee of C$20 million under certain circumstances if the deal isn’t completed.