Mining giant Freeport-McMoRan has bought the long-closed Twin Buttes Mine site, near Sahuarita, for $200 million and may mine it once again, company officials said Monday.

Phoenix-based Freeport-McMoRan Copper & Gold Inc. bought 8,900 acres of the open-pit mine site, which closed in 1994 after being mined since the 1960s, Freeport spokesman Richard Peterson said in a written statement. Smaller-scale mining operations in that area date to the 19th century.

The Twin Buttes Mine, run by companies including Anamax and Cyprus-Sierrita during its lifetime, adjoins Freeport's existing Sierrita Mine, which is seven miles west of Green Valley.

Freeport needs to conduct studies to determine the property's best use, but the purchase offers "the potential for additional mining activities and access to material that can be used for Sierrita tailings and stockpile-reclamation purposes," Peterson wrote.

The company would say nothing more about its plans for the site, which is about 20 miles south of Tucson. Nor would it say if the run-up in copper prices over the past year contributed to its decision to buy Twin Buttes.

But two longtime, local mining economists said a reopened Twin Buttes Mine could fare well, at least in the future, assuming the country climbs out of the recession and copper prices stay high or keep rising.

The prospect of a Twin Buttes Mine reopening at an existing mine site also didn't draw nearly as much heartburn from environmentalists as has the proposed new Rosemont Mine, which would disturb thousands of acres in the Santa Rita Mountains. But a key question would be where the water would come from to run it, an economist and several industry critics said.

The Twin Buttes site contains more than 700 million tons of mineralized material, the company's statement said. Its copper grade exceeds that of the Sierrita Mine - 0.43 percent copper, compared with 0.26 percent - and approaches the proposed Rosemont Mine's 0.47 percent.

Asked about the prospects of a Twin Buttes reopening, retired University of Arizona mineral economist Michael Rieber said: "Now, you're looking at a time of recession, no. But looking down the road, sure. The mines over their lifetime increase, decrease and disappear. They have to be replaced. Otherwise they are just losing output."

If the country fully recovers from the recession and home building resumes its pre-recession boom, the mine would do well, Rieber said. It still would take three to five years before Twin Buttes could get into full production. How quickly the mine reopens would depend on its existing condition, he said.

"I would suspect that the old mine was not completely closed, because then to do so they would have to start remediation," Rieber said, adding that one question would involve the water source.

The demand for copper at its current price of about $3.39 per pound - up from $1.55 at the recession's peak a year ago - is high enough to justify reopening Twin Buttes as well as building the Rosemont Mine, southeast of Tucson, and the Resolution Copper Corp. mine, proposed for the Superior area, said George Leaming, a mining economist for the Western Economic Analysis Center in Marana.

"Oh, sure it is, if they keep their costs in line," Leaming said Monday. "The market is there, as long as people keep buying copper. Copper is an energy metal. As long as we keep finding different ways to generate energy, these solar farms and wind farms are all going to take copper."

Jamie Sturgess, a vice president of Rosemont Copper's parent company, agreed, saying: "The demand for copper is such that the demand can support more operations. It is large and increasing."

News of Freeport's Dec. 30 purchase of Twin Buttes first surfaced in a recent annual earnings statement for the company.

Freeport has leased all or part of the Twin Buttes site for its use since 1988, Freeport's Peterson said. The Arizona Department of Environmental Quality had issued the company a permit to process copper from Sierrita at the Twin Buttes site, but to reopen the mine, the company would need a modified or new permit to ensure that its future discharges don't harm the aquifer, DEQ spokesman Mark Shaffer said.

Environmentalists Roger Featherstone and Nancy Freeman, who are Rosemont Mine opponents, said they either will support or will not be strongly inclined to oppose reopening of Twin Buttes.

Pima County Administrator Chuck Huckelbery said he also isn't inclined to oppose it, adding that he hopes Freeport would be a good neighbor regarding air and water quality and would use Central Arizona Project water to process ore rather than groundwater.

"It could be a situation that if they did it right, it might not be that big of a deal," said Featherstone, director of the Arizona Mining Reform Coalition. "Without knowing exactly what they wanted, it's hard to say, but it wouldn't set off alarm bells like Resolution or Rosemont."

But Pima County Supervisor Ray Carroll, whose district includes Green Valley, said he'd rather see the mines in the Green Valley area "retract, rather than expand, so they'd be further from residents."

Carroll said he would like Freeport to take comments from the broader community, including his own comments, to help decide what to do with the site.

"Now that this is out in the open, I hope they will explain to us what their intentions are. . . . I hope they take time to understand and explain what the upside is of the mine to Pima County, not just its stockholders," Carroll said.

"Copper is an energy metal. As long as we keep finding different ways to generate energy, these solar farms and wind farms are all going to take copper."

George Leaming, mining economist for the Western Economic Analysis Center in Marana

Contact reporter Tony Davis at 806-7746 or