New Mexico Mineral Symposium — Abstracts

Manganese minerals are widespread throughout Arizona. During the world wars a large amount of manganese was mined in Arizona, and the Artillery Peak area of west-central Arizona contains manganese deposits rated as among the four or five largest low-grade manganese mineral deposits in the United States (Chapman 1962).

There are more than 70 minerals that contain manganese found in Arizona (Anthony et al. 1995). Several of the Arizona manganese minerals are found in pegmatites, including the 7U7 Ranch locality. The 7U7 Ranch is the type locality for two manganese minerals, bermanite and paulkerrite. Manganese minerals are also commonly found associated with copper, silver, lead, and zinc deposits in Arizona. The type locality for coronadite is the west end of the Coronado vein near Morenci. In many of these veins the manganese is present as oxides included in black calcite veins. So, why is there manganese oxide and calcite in these veins instead of rhodochrosite?

Mineral collectors probably do not think of Arizona as a state that has produced fine specimens of rhodochrosite, and they are right. Although the rhodochrosite from Arizona does not compare with specimens from Colorado, there are a number of interesting localities. The Mineralogy of Arizona (Anthony et al. 1995) 13 rhodochrosite localities for the state.

The earliest described rhodochrosite from Arizona was found in Bisbee at the Junction mine, 1500 level, 78 stope and the Briggs mine, 1500 level, 104 stope by Bateman et al. (1914). It was found at the Trench mine in Santa Cruz County with alabandite, the manganese sulfide, by Schrader and Hill (1915). Similar occurrences of rhodochrosite with alabandite are reported from the Lucky Cuss mine in Tombstone, Higgins mine in Bisbee, and the Humbolt mine in the Chiricahua Mountains—all in Cochise County, Arizona, and described by Hewett and Rove (1930).

The best rhodochrosite in Arizona comes from the 2300 level of the Junction mine in Bisbee. The following is a description of this occurrence by Richard Graeme, unpublished manuscript, Mineralogy of Bisbee (2004).

"This was the most prolific locality for rhodochrosite in the district. Here it was usually found as massive material in alabandite and associated with sphalerite. It also rarely occurred as small, pale pink tabular crystals in massive alabandite and as 2 mm highly modified scalenohedrons in small voids in alabandite. These voids were usually at the limestone contact with the sulfides."

Other localities of interest include the Magma mine in Superior, Arizona, with rare small pale pink to red crystals in the south vein described by Barnes and Hay (1983) and collected by one of the authors. Nodules of iron oxide and rhodochrosite are reported from the Chinle Formation in Antelope Valley near St. Johns, Apache County. Finally, a 4-ft-wide rhodochrosite vein is reported at a depth of 120 ft in the shaft of the London Range mine in the Banner district, Gila County (Ross 1925). Unfortunately, the exact location of this mine and the rhodochrosite vein are not known.

References:

1. Anthony, J. W., Williams, S. A., Bideaux, R. A., and Grant, R. W., 1995, Mineralogy of Arizona: University of Arizona Press, Tucson, Arizona, 508 pp.
2. Barnes, R., and Hay, M., 1983, Famous mineral localities???the Magma mine: Mineralogical Record, v. 14, pp. 72-82.
3. Bateman, M. N., and Murdoch, J., 1914, Secondary enrichment investigations; notes on Bisbee, Arizona: Unpublished notes, Harvard University, Mineralogical Museum files, 240 pp.
4. Chapman, T. G., editor, 1962, The mineral industries of Arizona: Arizona Bureau of Mines, Bulletin 169, 20 pp.
5. Hewett, D. F., and Rove, 0. N., 1930, Occurrence and relations of alabandite: Economic Geology, v. 25, pp. 36-56.
6. Ross, C. P., 1925, Geology of the Saddle Mountain and Banner mining districts: U.S. Geolgical Survey, Bulletin 771, 72 pp.
7. Schrader, F. C., and Hill, J. M., 1915, Mineral deposits of the Santa Rita and Patagonia Mountains, Arizona: U.S. Geological Survey, Bulletin 624, 412 pp.