In August, Interior Secretary Ken Salazar visited Oak Flat, a boulder-strewn patch of land scattered with manzanita bushes and oak trees, about 70 miles east of Phoenix. Salazar was there to gather information on a proposed land exchange between the federal government and Resolution Copper Co., a branch of the global mining giant Rio Tinto. If Congress approves the deal, Oak Flat will become the mining company's property, and the feds will get thousands of acres of land along the San Pedro River and elsewhere in Arizona. Regardless of whether they support or oppose the deal, most observers agree that, since it was first set in motion five years ago, it has become a tangled mess. The swap is mired in a far-reaching scandal that has left former Arizona Republican Rep. Rick Renzi battling federal fraud charges. Opponents of the deal — notably area tribes — have stalled it