Old Baldy prospects, Littleshot Camp, Madera Canyon, Old Baldy Mining District, Santa Cruz County, Arizona, USAi

Regional Level Types
Old Baldy prospects	Group of Prospects
Littleshot Camp	- not defined -
Madera Canyon	Canyon
Old Baldy Mining District	Mining District
Santa Cruz County	County
Arizona	State
USA	Country

‡Ref.: Hill, J.M. (1912) The mining districts of the western United States, with a Geologic Introduction by Waldemar Lindgren: U.S. Geological Survey Bulletin 507, 309 p.

Schrader, F.C. & J.M. Hill (1915), Mineral deposits of the Santa Rita and Patagonia Mountains, Arizona, USGS Bull. 582: 168, 176-177.

Drewes, H.D. (1971) Geologic map of the Mount Wrightson quadrangle, southeast of Tucson, Santa Cruz and Pima Counties, Arizona: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-614, 1 sheet, scale 1:48,000.

Drewes, H.D., 1972, Structural geology of the Santa Rita Mountains, southeast of Tucson, Arizona: U.S. Geological Survey Professional Paper 748, 35 p., scale 1:12,000, 4 sheets.

Lenon's map of Santa Cruz County.

U.S. Bureau of Mines file data, Old Baldy prospect.

U.S. Bureau of Mines field notes CU58.

MRDS database Dep. ID file #10037132, MRDS ID #M030557; and, Dep. ID #10210494, MAS ID #0040230305.

A series of underground Cu-Pb-Au-Ag-Mo-Fe prospects with underground workings located 1½ miles north of Littleshot Camp and ¼ mile north of the Lucky Ledge Mine, at an elevation of about 6,375 feet. Owned by Louis Littleshot & Co. NOTE: Alternate coordinates provided: 31.7156N, 110.8692W.

Mineralization is a 2 foot wide quartz vein contained in a mass or small stock of lamprophyric "spotted porphyry," which is intruded into the micaceous quartz schist. Both the porphyry and the schist are sheeted parallel with the vein. The porphyry consists of a holocrystalline groundmass of orthoclase, biotite, albite, oligoclase, and magnetite, and an earlier generation of biotite, orthoclase, oligoclase, and magnetite phenocrysts, many of which are 1/8 inch long. Much of the feldspar is highly sericitized. The vein dips 60ºSE. Some galena and chalcopyrite occur in bands 1 inch to several inches wide in bunches, mostly in iron-stained quartz, and reportedly caries moderate quantities of Ag & Au. The host rock unit is the Madera Canyon Granodiorite. An associated rock unit is the Gardier Canyon Rhyolite Porphyry. Local structures include the NE-trending Box Canyon dike swarm. Tectonic elements include the Mt. Wrightson Fault Block.

Workings include a 65 foot long drift.

Several additional prospects occur within several hundred feet of the one just described, to the north and to the north of each other.

The first, a few hundred feet north, features altered schist on the hanging wall of a banded quartz vein showing comb structure and dipping 60ºESE. The altered schist contains bodies of coarsely crystalline, variously colored calcite ranging from white to black.

Another 300 feet north the schist contains an 'iron ledge' consisting of 15 feet of more or less epidotized iron-bearing schist dipping 55ºSE, and having on its footwall a 4 to 6 inch (10 to 15 cm) banded quartz vein showing comb structure and containing some chalcopyrite, malachite, and iron oxide. All of these prospects are associated with or near lamprohyric porphyry dikes.

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Link to USGS MRDS:	10037132

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