A map shown to potential investors by Rosemont Mine's parent company shows three copper "targets" in areas lying west of the currently proposed open-pit mine site.
If those additional areas were eventually mined, they would be visible to Green Valley, a stronghold of Rosemont opposition.
The map appears on Augusta Resource Corp.'s website as an investor presentation.
But Gil Clausen, Augusta's president and CEO, said Wednesday that the company has no plans to mine these areas, which lie atop or west of the ridgeline in the Santa Rita Mountains. They sit directly west of the proposed mine that is now undergoing federal environmental review.
Augusta-owned Rosemont Copper is, however, looking at the potential for future copper mining east of that ridgeline, Clausen said. It is conducting electric-based, underground geophysical exploration to see if those lands could have significant copper deposits.
Once those surveys are finished next year, the company will decide whether they merit actual drilling, Clausen said.
If those areas ever pan out, that could stretch mining in that area beyond the Rosemont Mine's expected 21-year life, although the company would need a second round of environmental reviews to mine any new deposits.
But atop and west of the ridgeline, "we don't see any resource potential there," Clausen said. "We don't intend to do any mining development there. We're just trying to let people know where those deposits are."
The mine's environmental impact statement will be discussed at a public meeting today in Green Valley, where some opponents have feared that Rosemont's plans do extend west of the Santa Ritas' ridgeline.
Pima County Supervisor Ray Carroll, a mine opponent who represents Green Valley, said the company is being "very duplicitous for trying to present one story to people to get public approval, while they're telling investors a whole different story."
"It's just a matter of whether taxpayers and voters will wake up to them hoping that if they get their foot in the door with the Rosemont site, that they plan to move west into the Green Valley-front range," said Carroll, a Republican.
The "target" deposits are:
• Broadtop Butte, known to contain about 9 million tons of copper ore, compared with an expected 666 million tons at the proposed Rosemont Mine site. Broadtop Butte lies within the area where Rosemont Copper is conducting geophysical explorations.
• Peach Elgin, estimated to contain 23.4 million tons of ore.
• Copper World, which the map says has no historical resources but describes as an "exploration target," while the others are simply called "targets."
They are called targets only because they are the sole known "expressions of resources" that make it to the ground surface, Clausen said. Officials know from past drilling that these areas are cut off from other deposits by shallow, low-angle faults and that the areas below are unmineralized, he said. Most likely, these smaller deposits came from larger deposits on the ridge's east side.
"That is why we will continue to explore the east side to unlock the geologic puzzle," Clausen said. "We do know the size and extent of Rosemont and have it very well defined."
For some years, mine opponents have raised concerns about these sites due in part to their visibility from Green Valley.
In 2007, Clausen told a mining magazine that the sites, already held by the company, had promise.
"Mr. Clausen noted that, although developing Rosemont was the company's primary focus, the three other properties offered opportunities for further exploration, especially ... Broadtop Butte, as the Rosemont deposit is open to the north and east directly toward where Broadtop is located," said the article in World Mining Stocks, which described all the sites as part of a "strategic land package."
But Clausen said Wednesday, "Our knowledge of the land holdings has increased significantly since 2007 ... and the east side is our focus, not the west."
Gayle Hartmann, president of mine opposition group Save the Scenic Santa Ritas, said she continues to be suspicious about these deposits, in part because of Clausen's 2007 statement.
"I would be very concerned if I lived in Green Valley or Sahuarita that new mining activities would blast away at the ridgeline," Hartmann said.
Stan Riddle, president of the nonprofit Green Valley Council, which opposes Rosemont, said his main concern about the exploration map is about the extra water needed to serve mined areas east of the ridge.
"To me that is a real big issue, because we only have so much water now, and there is an overdraft every year from existing mines and agriculture in our area," he said.
But the president of a Tucson reclamation and excavation firm, Mike Ferris of Lamb Inc., said he thinks public reaction would be positive to additional mining in the Rosemont area if, in the meantime, the company carries out its promises to run what it has called a sustainable, 21st-century mine.
On StarNet: Read more environment-related articles at azstarnet.com/news/science/environment
If you go
• What: Public meeting on the Forest Service's draft environmental impact statement for the Rosemont Mine.
• When: 12:30 to 4:30 p.m. today.
• Where: Green Valley Recreation West Social Center, 1111 Via Arcoiris, Green Valley.
Contact reporter Tony Davis at email@example.com or 806-7746.