New Mexico Mineral Symposium — Abstracts

In 1846 Lieutenant William H. Emory led a detachment of topographical engineers across an area southwest of Santa Fe for the purpose of establishing wagon roads. After visiting the Copper mines at Santa Rita, the group moved to the Gila River and down that waterway to camp at a point at what is now the border between New Mexico and Arizona. To the north the group observed a distinctive rock formation and by consensus named the edifice Steeple Rock. The name was duly noted in the margin of their survey map. It was not until the 1860s that mineralization was noted northwest of Steeple Rock. However, it was not until 1880, after the Indian threat had abated, that the Steeple Rock district was organized and mining begun. The district is located about 15 mi northeast of Duncan, Arizona, approximately 3 mi inside Grant County, New Mexico. The district, from 1880 to 1993, produced approximately 151,000 oz of Au, 3.4 million oz of Ag, 1.2 million lb of Cu, 5 million lb of Pb, 4 million lb of Zn in addition to commercial amounts of fluorite and manganese. At present the Summit mine is being prepared for commercial mining. Production is projected to start in early spring of 2009 with milling taking place at a locality near Lordsburg.

Rocks exposed in the Steeple Rock district are essentially a sequence of Tertiary units consisting of andesite, basaltic andesite, and dacite lavas. Mineralized epithermal quartz veins are structurally associated with generally northwest-southeast trending faults. Vein matter consists of quartz as much as 10 ft wide with some reaching several miles long. Ore minerals include: gold, silver, acanthite, galena, sphalerite, chalcopyrite, pyrite, and associated minerals. Published mineral species for the district include: acanthite, albite, alunite, augite, azurite, barite, biotite, calcite, chalcocite, chalcopyrite, chlorite sp., chrysocolla, dufrenite, epidote, fluorite, galena, gold, hematite, jarosite, kaolinite, limonite sp., magnetite, muscovite, orthoclase, plumbojarosite, pyrite, pyromorphite(?), quartz, silver, tetrahedrite, and vanadinite(?). Species new to the district include: aurichalcite, brochantite, cerussite, chalcanthite copper, cuprite, descloizite, dolomite, duftite, goethite, gypsum, libethenite, malachite, mimetite, mottramite, pyrolusite, siderite, smithsonite, vanadinite, and willemite.

Most of the larger mines have been patented or otherwise are located on private property, and permission to collect must be obtained for access. Roads are gravel or compact dirt and include Carlisle Road approaching from the southwest and Bitter Creek Road approaching from the northwest, both of which are well marked and county-maintained.

Although the Steeple Rock district did not appear to have many possibilities for collectable mineral specimens when researching the published data, on the ground searching of the dumps and mines turned up a surprising number of collectable items. However, only a cursory examination was conducted during the current study for some of the more than 60 significant mines around the district. Additional systematic examination is sure to turn up many more interesting minerals. As a reminder, this is an active mining area, and caution should be exercised to avoid mining activity on the haulage roads and mine sites. It should be additionally noted that several large rattlesnakes were encountered during this study, all in the southern part of the district.

Acknowledgments
Special thanks are extended to Dr. Anthony Kampf, Natural History Museum of Los Angeles. ounty, and Dr. Robert Housely, Pasadena, California, for mineral specimen analyses, and to Leslie Billingsley and Richard Billingsley for allowing access to private property in the district.

References:

1. Gillerman, E., 1964, Mineral deposits of western Grant County, New Mexico: New Mexico Bureau of Mines and Mineral Resources, Bulletin 83, 213 pp.
2. Griggs, R. L., and Wagner, H. C., 1966, Geology and ore deposits of the Steeple Rock mining district, Grant County, New Mexico: U.S. Geological Survey, Bulletin 1222-E, 20 pp.
3. Hedlund, D. C., 1990, Geology and mineral deposits of the Steeple Rock and Duncan mining districts, Grant and Hidalgo Counties, New Mexico, and Greenlee County, Arizona: U.S. Geological Survey, Open-file Report 90-239.
4. McLemore, V. T., 1993, Geology and geochemistry of the mineralization and alteration in the Steeple Rock district, Grant County, New Mexico, and Greenlee County, Arizona: Unpublished Ph.D. dissertation, University of Texas, El Paso, and New Mexico Bureau of Mines and Minerals Resources, Open-file Report 397.
5. Northrop, S. A., 1996, Minerals of New Mexico, 3rd ed., revised by F. A. LaBruzza: University of New Mexico Press, Albuquerque, 346 pp.