Early 1900s – Small-scale pick-and-shovel mining began in the Rosemont valley.
1994 – Asarco Mining Co. completed its consolidation of about 2,000 acres in private holdings at Rosemont under the General Mining Law of 1872, which allowed the company to purchase large swaths of public land containing billions of dollars worth of minerals from U.S. taxpayers. Asarco purchased these land swaths for just $5 per acre.
1995–1997 – Asarco attempted to acquire more than 13,000 acres of public land in the Rosemont area in a land exchange with the federal government, while offering only about 2,000 acres in return.
January 1998 – In the face of falling copper prices and a vigorous grassroots opposition campaign, Asarco gave up on its plan for Rosemont.
2005 – Augusta Resource Corp., a speculative Canadian mining company that had never operated a mine, acquired the Rosemont holdings and began planning to construct a large open-pit copper mine through an Arizona subsidiary, Rosemont Copper Co.
2006 – Augusta filed a "mine plan of operations" with the Coronado National Forest, which kicked off the process of developing an environmental impact statement (EIS) to analyze the proposed mine's impacts. The Center worked with coalition partners to submit formal comments on various stages of the EIS over the next several years.
2011 – The Center, with allies, filed a lawsuit against the Coronado National Forest under the Federal Advisory Committee Act for violations stemming from the presence of Rosemont officials and the exclusion of the public in closed meetings during which Rosemont EIS issues were discussed and developed. A federal judge sided with the Center and our partners, stating that "the actions [of the Forest], at a minimum, present an appearance of impropriety on the part of the U.S. Forest Service as well as Rosemont" – but the judge did not stop the EIS process from moving forward.
September 2011 – The draft EIS was issued, which prompted the U.S. Environmental Protection Agency to likewise issue the first of a series of scathing letters criticizing the Rosemont proposal and recommending that it not proceed as proposed, assigning the draft EIS an "unsatisfactory" rating, which it has given out only a handful of times over the course of 40 years and tens of thousands of such documents.
May 2012 – The Center and coalition allies filed an administrative appeal of an aquifer protection permit issued to Rosemont by the Arizona Department of Environmental Quality.
September 2012 – A male jaguar was photographed in the Rosemont area, very close to the location of the proposed open-pit mine. The jaguar has showed up repeatedly on remote sensor cameras ever since, showing that it is clearly been using the Santa Rita Mountains and Rosemont area as its home range.
January 25, 2013 – The EPA sent a letter to the U.S. Army Corps of Engineers detailing the shortcomings of Rosemont Copper Co.'s proposed mitigation plan and recommending against permitting of the mine.
July 2013 – The proposed mine's aquifer-protection permit appeal was denied by Arizona's Water Quality Appeals Board by a vote of 2–1, despite board members admitting on the record that they had not had time to review the facts of the case surrounding the permit.
August 2013 – The Center, along with coalition allies, filed a lawsuit in Arizona Superior Court to overturn the appeals board's decision on the aquifer-protection permit.
November 2013 – The U.S Fish and Wildlife Service issued a formal biological opinion concluding that the proposed Rosemont mine would not jeopardize or unduly harm a dozen (plus) threatened and endangered species in the area. The Coronado National Forest issued a final EIS and a "draft record of decision" concluding that the project should go forward.
January 2014 – The Center and coalition allies filed a package of about 100 formal objections to the Coronado's decision, a precursor to a lawsuit to overturn the Coronado's proposed decision to allow the project to proceed.
March 2014 – The Fish and Wildlife Service finalized critical habitat for the jaguar, including thousands of acres falling within the Rosemont project area.
May 2014 – In the face of new species listings, the discovery of an endangered ocelot in the Rosemont area, and new information about the damage that Rosemont would do to such nearby aquatic resources as Cienega Creek, the Fish and Wildlife Service retracted its biological opinion and reinitiated consultation on endangered species issues, which essentially froze the permitting process.
August 5, 2014 – The Center sent a letter to the Fish and Wildlife Service outlining problems with the initial, withdrawn biological opinion and urging the Service to carefully reconsider impacts to endangered species.
2014 – Another Canadian mining firm, HudBay Minerals, Inc., successfully completed a hostile takeover of Augusta Resource Corp. and gained control of the Rosemont project.
Fall 2014 – HudBay initiated supplemental exploratory drilling in the proposed Rosemont pit area. The Center and coalition allies filed a 60-day notice of intent to sue the Coronado National Forest for failure to consult with the Fish and Wildlife Service on the potential impacts of the drilling activity on endangered species in the area.
February 29, 2016 – Hudbay Minerals Inc. announced a construction delay for its proposed Rosemont Copper Mine in the Santa Rita mountains near Tucson.
May 3, 2016 – The U.S. Fish and Wildlife Service issued its final biological opinion giving approval to the mine despite admitting that it would destroy the home of America's only known jaguar and harm a number of other imperiled species.
July 29, 2016 – The U.S. Army Corps of Engineers' Los Angeles regional office has recommended denial of an essential permit for the proposed Rosemont copper mine.
June 6, 2017 – The U.S. Forest Service signaled its approval of the proposed Rosemont mine, despite lacking key permits and reviews.