Carroll

Oracle Ridge Mine on Mount Lemmon, The Star is Confused

A front page story in today’s Arizona Daily Star reports that the Oracle Ridge copper mine on Mt. Lemmon, near Summerhaven, might be reopened. The story contains some errors.

The Star’s story says, “The mine was producing about 1,000 tons of copper a day at the time it closed… Those estimates are much larger than the expected production from the proposed Rosemont Mine in the Santa Rita Mountains, southeast of Tucson. Rosemont’s owner said it would produce about 301 tons per day for 20 years, starting in 2012.”

The Star’s error lies in confusing tons of rock mined with tons of copper metal contained in the rock. The Oracle Ridge mine was producing 1,000 tons per day of rock which contained just over 2% copper, as well as some value in gold and silver.

Rosemont’s projected production refers to tons of copper metal. Rosemont’s proposed production of 301 tons of copper per day would have a gross value of $1.9 million per day (at today’s spot price for copper of $3.23 per pound). Oracle Ridge, producing 1,000 tons of rock, grading 2% copper, means Oracle Ridge would produce 20 tons of copper per day, with a gross value of $129,000. (Note: Profit, if any, is gross value minus all expenses, taxes, and fees.)

There is more confusion in the Star’s story: “News clippings from the time the Oracle Ridge mine was operating showed a much lower production rate, [than the 1,000tons] however. Tom Olsen, the mine’s general manager in the 1990s, told the Star in 1992 that it produced about 50 tons daily, or enough to fill two truckloads with copper concentrate.” Here the Star is confusing tons of copper concentrate with tons of rock. Copper concentrate is produced from a flotation process that separates most of the copper minerals from the enclosing rock. Copper concentrate is smelter feed and typically contains 30% copper (at least at the large porphyry copper plants). The 50 tons of concentrate, reported as shipped, would contain about 15 tons of copper metal.

The Oracle Ridge mine was discovered in 1900 and has had spotty production since 1937. The last production was from 1991 to 1996. In 1994, Mintec, a consulting firm specializing in ore estimation, was contracted to complete a reserve estimate as part of a feasibility study for increasing the mine and processing plants capacity to 2,000 tons per day. The Mintec model estimated 8.14 million tons of proven and probable ore at a grade of 2.33% copper containing 379,000,000 lbs of copper and an additional possible or inferred resource of 16.57 million tons at 2.33% copper containing an additional 772,000,000 lbs of copper. No allowance was made for dilution, mine loss or pillars left in place, and gold and silver grades were not estimated. The data base for these estimates included 534 drill holes totaling 163,622 feet.

I visited the mine during that time to evaluate it for the major mining company I worked for (or for strict grammarians, the company for which I worked). The mine was considered too small to be of interest to a major mining company, but it could make a good small mine for a junior company.

The Oracle Ridge mine is on patented mining claims, i.e., private property. The Star’s story also said that “County Supervisor Ray Carroll, a vocal opponent of the Rosemont proposal, said he will lead the opposition to reopening of the Oracle Ridge Mine. Republican Carroll’s district includes that site and the Rosemont site.” It seems that Mr. Carroll doesn’t want any much-needed jobs or economic development to despoil the grandeur of nature in his district, property rights notwithstanding.

UPDATE: Following publication of this story, the Star reporter called me. The original story in the Star has been changed reflecting my comments. The reporter is trying to verify the original data in the press release by the company interested in buying the property.

And, a correction of my own: some sources say the mine was worked as early as 1881.

Local Politicians Against Jobs

Southern Arizona is blessed with abundant mineral resources, and cursed with a Congressional delegation and county supervisors, such as Ray Carroll, who would deny us that blessing.

Representatives Gabrielle Giffords and Raul Grijalva have introduced HR2944, the Southern Arizona Public Lands Protection Act of 2009 into the House. This bill would prohibit staking of mining claims, mineral leases, and geothermal projects on all federal land in Pima and Santa Cruz Counties (subject to pre-existing rights). This is essentially a response to the Rosemont mining venture.

Apparently, these politicians are not in favor of good jobs or economic opportunity.

According to testimony before the House Subcommittee on National Parks, Forests and Public Lands, the Steelworkers union opposes the bill. “HR 2944 is bad public policy. The bill would completely bypass the federal EIS process put in place under the National Environmental Policy Act for consideration of proposed mining and minerals operations that involve public lands. The EIS (environmental impact statement) process involves state and local agencies on a collaborating basis and works well to thoroughly examine proposed projects. Congressional intervention to enact land use and resources development policy on a county-by-county basis is a bad idea. In addition, job creation would be sacrificed in this bill. Mining plays a strong economic role and has done so for more than a century in Arizona.”

“In Arizona, the average mining job pays $60,000, which is 44% higher than the average pay in the state. Tourism and retail jobs on the other hand pay, on average, about half this amount or just over $29,000. In addition, for every new mining job, another 4 indirect jobs are created. Arizona is home to 411 mining operations that provide direct employment to about 18,480 people and another 34,360 people indirectly from mining activity occurring both in and outside the state for a total of 52,840 jobs statewide.”

The law is also poorly written and may have unintended consequences. For instance, the law would prohibit “all forms of entry, appropriation, and disposal under the public land laws.” The word “entry,” in what I think is the intended context, means “mineral entry” the terminology used for staking and registering a mining claim. But, as written, the law could be construed to prohibit cattle grazing, hunting, hiking, other forms of recreation, and use by the border patrol. The only “entry” we will see is by illegal aliens and drug smugglers.

To give you some idea of the mineral potential of Pima County and the folly of HR2944, I present below, excerpts from a 2001 publication, “Mineral Potential of Eastern Pima County, Arizona” published by the Arizona Geological Survey as Contributed Report 01-B. This report was written in response to Pima County’s Sonoran Desert Conservation Plan by The Southwestern Minerals Exploration Association, a group of local geologists (I am a co-author of the report).

Mineral production has always been viewed as an essential industry, not only to generate wealth and provide employment, but also for the array of products that are consumed by a society. Terms such as Bronze Age and Iron Age have served to demonstrate the essential role of minerals in improving a society’s standard of living. Today, in what we have come to call the Technology Age, the demand for minerals and mineral-bearing products has grown exponentially. This is not surprising, over the last four thousand years, societies with mineral technologies have flourished, while those lacking mineral resources have either conquered to take others, or have ultimately perished.

Mineral production is essential to our civilization because minerals provide the raw materials which allow our society to function. Pima County is endowed with many mineral resources, not only copper mines, but also the important products such as sand, gravel, and limestone used everyday in supporting the infrastructure of our cities. It is essential that these mineral resources, and the lands where they occur, remain available for exploration and development.

Pima County has a unique, and complex, geological history which makes it critical habitat for large copper deposits, geothermal resources, and many industrial minerals such as sand, gravel, gypsum, and limestone. This report documents known occurrences of these mineral deposits, and delineates areas with the greatest potential for future discovery of additional mineral deposits, based on existing geological and geochemical data, and upon proven methods of investigation.

Spencer R. Titley, University of Arizona Professor, wrote in 1982: “The porphyry copper deposits of southeastern Arizona and contiguous regions compose one of the richest copper metallogenic provinces on earth and perhaps the richest of seven separate porphyry copper provinces which surround the Pacific Basin. At least thirty-five separately named significant occurrences of porphyry-intrusion-related concentrations of copper occur here and the

record of discovery suggests that more will be found.” (Titley, Spencer R., 1982, Advances in Geology of the Porphyry Copper Deposits, Southwestern North America: University of Arizona Press, Tucson Arizona 560 pp.)

The first map below shows the distribution of known copper deposits in Pima and Santa Cruz Counties. The red color show outcrops of Laramide intrusives, which can be the generators of the mineral deposits. The brown shows outcrops of older host rocks. Additional potential occurs in the valleys under cover.

EPCcopperdeposits

The next map shows the mines and areas that hold additional potential for discovery in Pima County. The broad orange arcs are areas favorable for exploration and discovery of porphyry copper deposits as defined by members of the Southwestern Mineral Exploration Association. The yellow areas (e.g. G-1) are tracts permissive for the occurrence of porphyry copper deposits defined by the U.S.Geological Survey in OFR 90-276 “Preliminary Mineral Resource Assessment of the Tucson and Nogales 1 x 2 Quadrangles, Arizona.” The green areas (e.g. T-1) are tracts favorable for the presence of undiscovered mineral deposits – High Potential Tract defined by the U. S. Geological Survey in Bulletin 2083 A-K “Resource Potential and Geology of Coronado National Forest, Southeastern Arizona and Southwestern N.M.”

EPC-favorable-copper-areas

The next map shows (in blue) the geothermal potential in Pima County. This is a low temperature resource suitable for space heating and cooling for industrial parks and residential developments such as apartments, town houses, condominiums and neighborhoods composed of single-family dwellings. This type of resource is also suitable for aquaculture and greenhouse agriculture. Studies show that 30 degree C water is ubiquitous at depths of 300m and that potential exists for potential for 50- to 55 degree C water at a depth of 1,000 m.

The red area is a mercury anomaly which sits below our water recharge project in Avra Valley (does Tucson Water know about this?). Not to worry though, the mercury anomaly is 75-750 ppb Hg while ADEQ allowable residential standard is 6,700 ppb Hg. (Reference: Hahman, W. R. and Allen, T. J., 1981, Subsurface stratigraphy and geothermal resource potential of the Avra Vally, Pima County Arizona: Arizona Bureau Geol & Min. Technology, OFR 81-5).

EPCgeothermal

The American mining industry pioneered Arizona. For more than one hundred years, metal and aggregate companies have operated under the rules and regulations set out in legal frameworks.

Few anticipated that they would lose access to land for future mineral development. Viewed as a societal good, access to the land encouraged growth. The mineral products provided much needed materials for construction, trade, and local economies. Land-use planning was motivated by economic development needs, manifest in the desire for improved tax bases and infrastructure. Therefore mining plays a key role. We should not let short-sighted politicians deprive us of these benefits.

(Disclaimer: I spent my professional career exploring for and helping develop mineral deposits, and I worked for a major mining company. I have, however, no connection with Rosemont or Augusta Resources.)