New Mexico Mineral Symposium — Abstracts

There are 810 mineral species described from Arizona in the second edition of the Mineralogy of Arizona (Anthony, Williams, Bideaux, and Grant, in press). The first edition published in 1977 had 584 mineral species listed for Arizona; 226 minerals, an average of 14 minerals per year, have been added for the last 16 years. There are several reasons for this increase in the rate of identifica¬tion and discovery of new minerals in Arizona. They include better techniques for mineral identifica¬tion with the use of equipment like the electron microprobe, a high level of interest in rare minerals by mineral collectors, and the detailed study of some unusual mineral deposits found in Arizona. These deposits include the pegmatites of the Basin and Range, the breccia pipes of the Colorado Plateau, and the Campbell sulfide deposit at Bisbee.

Granite pegmatites are widespread throughout Arizona. They are abundant in the older Precambrian terrain of the Grand Canyon and in the Precambrian rocks of the Arizona pegmatite belt. This area, from the northwest corner of Arizona trending 250 mi southeast to the Phoenix area, encompasses part of the Transition zone and the Basin and Range Province. More than 120 different minerals have been reported from pegmatites in Arizona. Many of these minerals are the result of a complex sequence of alteration of the primary pegmatite minerals.

The Hack 1, Hack 2, Hack 3, Hermit, Pigeon, and Kanab North breccia pipes were all brought into production as uranium mines in the 1980s. These breccia pipes are concentrated on the Colorado Plateau between the Grand Wash Cliffs and the Echo Cliffs and along both the north and south sides of the Colorado River. The uranium concentrations in the ore can be high: 0.3 to 0.6% uranium oxide or higher. Other elements that are enriched in these deposits include Sb, As, Ba, Cd, Cr, Cs, Cu, Co, Ga, Ge, Pb, Hg, Mo, Ni, Se, Ag, Sr, V, and Zn. The concentration of so many elements and the subsequent oxidation of some of these deposits have resulted in the formation of a large number of minerals. More than 100 minerals have been reported from these deposits.

Since mining began in the Bisbee area in 1877, more than 290 minerals have been found, making it the locality with the most mineral species in Arizona. Recent research in the area has been concentrated on the Campbell orebody. This orebody is a replacement of a limestone breccia by massive sulfides. The sulfide body—mainly pyrite with either chalcopyrite or bornite—contains small amounts of many rare Au, Ag, Bi, Cu, Hg, Ni, Sn, and Zn sulfides and tellurides.