In the last three years, Rio Tinto, an international mining company, has staked two large groups of mineral claims in the Santa Rita and Patagonia Mountains. The claim stakes typically bear the initials “KEX”, for Kennicott Exploration Company, an American subsidiary of Rio Tinto, the third largest mining company in the world.

Claims are generally rectangular, with length being limited to 1,500 feet, and width to 500 feet, making for a maximum of 20.67 acres, which is the most common size.                                                                                                     

To understand land-claiming on public lands, it is essential to know the difference between patented and unpatented claims. As part of the expansion of the American West, and shortly after the mid-19th century period of “mineral mania,” the patenting process was established by the General Mining Act of 1872. Under that Act, a claimant could apply to the Federal Government for a patent, given a proven indication of mineral locations on the property. The resulting patent document, signed by (or for) the President of the United States, conveyed both surface and mineral rights to the owner, and had the legal effect of a full deed to the property, at a cost of $5 an acre. Counties recognize patented claims as legal parcels of land and map them accordingly. 

The patenting of mineral claims was suspended in 1994, one of several adjustments to the 1872 Mining Act over its 147-year career. This has meant that for the last 25 years, all new claims have been unpatented, but can still be staked on unclaimed public land where there is no environmental preservation or other dedicated public use.

Unlike patented claims, unpatented claims grant the claimant subsurface mineral rights only, with surface management on public lands generally by the US Forest Service. This puts both mining and exploration under the regulation of the National Environmental Protection Act (NEPA), and other Federal, State and County regulations. The US Bureau of Land Management (BLM) sets the rules for filing and maintaining mining claims, keeps claim records and collects the filing fee and annual fees of $165 per claim, paid to maintain active status. 

From 2016 to 2019, Rio Tinto’s claim-staking campaign generated 1,787 claims in the Patagonia  and Santa Rita Mountains, roughly 11% of the 16,207 mining claims currently on file for Santa Cruz County lands. By the end of 2019, the company’s remaining active claims numbered 1,027, since about 40% of the total have become closed claims. There was a spike in closures in the fall of 2019. Kennicott’s reasons for the sudden closures have not been made public.

The accompanying map shows the two groups of Rio Tinto’s active unpatented claims, east and west of Patagonia and within about six miles of the town. The tinted areas are not the boundaries of claims themselves, just a location method, by quarter-section of land. Sprinkled around and within the claim groups are several patented claims, generally from legacy claims and artisan mining, and mostly closed. 

A further bit of complexity on the map is that mineral claims can sometimes be placed on seemingly private land, off of National Forest land, under the 1916 Stock Raising Homestead Act (SRHA), a cattle-oriented descendant of the 1862 Homestead Act, which grants ranchers surface rights for grazing but retains mineral rights for government decision-making. As a local example of the SHRA, Rio Tinto claims occur on both sides of Salero Road going away from Sonoita Creek, the district of the claim tag in the photo.

Altogether, Rio Tinto’s active claims occur over about 20,000 acres in two mountain ranges, a realm of complex hydrology and geology, overlapping mineralization and major biological diversity. Two interesting maps, from 1878 and 1950, posted in the entrance to the Patagonia Town Hall, show the historical context of the Rio Tinto claims areas.

“Future exploration” describes Rio Tinto’s interest in both the Patagonia and the Santa Rita Mountains. In early 2018, Kennicott Exploration Company performed an aerial prospecting survey in the Patagonia area, as reported in the May 2018 PRT. Rio Tinto’s local minerals of interest have not been publicly mentioned by the company, so it is not yet clear what they might be after, in this multi-mineral region. The “big five” mined in the area in the past two centuries have been gold, silver, copper, lead and zinc.                                                                             

The company has put forward no exploratory or drilling proposals to date. It may be changing its focus away from larger scale projects, according to a recent announcement by Lynn Olesson, a general manager at Rio Tinto’s Exploration Department.

Olesson said “Rio Tinto will now consider smaller resources that have the potential to grow if they have a moderate capital expenditure, are in jurisdictions with low political risk that don’t have large wealth inequality, and can be developed in a reasonable time frame.”