Heavy Weight Mine (Light Weight Mine), Heavy Weight Hill, Helvetia, Helvetia-Rosemont District, Santa Rita Mts, Pima Co., Arizona, USA
‡Ref.: Schrader, F.C. & J.M. Hill (1915), Mineral deposits of the Santa Rita and Patagonia Mountains, Arizona, USGS Bull. 582: 92, 110-113.
Photo: Chris Marcum
Johnson, V.H. (1941) Geology of the Helvetia mining district, Pima County, Arizona: Tucson, University of Arizona, Ph.D. dissertation, 111 p.
Creasey, S.C. & G.L. Quick (1955), Copper deposits of part of Helvetia mining district, Pima County, Arizona, USGS Bull. 1027-F: 301-323: 320.
Warner, L.A., Holser, W.T., Wilmarth, V.R., and Cameron, E.N. (1959) Occurrence of nonpegmatitic beryllium in the United States: U.S. Geological Survey Professional Paper 318, 198 p., 5 sheets, scales 1:480, 1:960, 1:4,800, 1:500,000: 103.
Drewes, H.D. (1971) Geologic map of the Sahuarita quadrangle, southeast of Tucson, Pima County, Arizona: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-613, 1 sheet, scale 1:48,000.
Keith, Stanton B. (1974), Arizona Bureau of Geology & Mineral Technology, Geological Survey Branch Bull. 189, Index of Mining Properties in Pima County, Arizona: 126 (Table 4).
USGS Sahuarita Quadrangle topo map.
Arizona Bureau of Mines field notes (1971), vol. 1, no. 2.
MRDS database Dep. ID file #10039409, MRDS ID M050042; and, Dep. ID #10186180, MAS ID #0040190248.
A former small underground Cu-Ag-Au-Be mine located in the SE ¼ sec. 14, T.18S., R.15E., ¾ mile NE of Helvetia and ½ mile NE of the Copper World and Leader Mines, 28 miles SE of Tucson, on private land. It lies on the steep southwest slope of Heavy Weight Hill, at the east end of a traverse ridge or spur. Comprised of the Heavy Weight and Light Weight claims. Discovered 1887. Opened late in the 1880's. Produced 1889-1902. Owned at times, or in part, by the Helvetia Copper Co.; Michigan-Arizona Development Co.; and the Helvetia Copper Co. of Arizona.
Mineralization is irregular, pyrometasomatic replacement orebodies containing copper carbonates and sulfides in silicified, garnetized, sheared, and thrust-faulted Paleozoic Concha limestone along a contact with reddish-gray Laramide quartz latite porphyry intrusive. The shear zone strikes S25W and dips steeply SE. The rocks have been locally considerably disturbed, sheared, and faulted. The intrusive rock has a fine-granular groundmass of orthoclase, oligoclase, quartz, and hornblende in which rest phenocrysts to 0.4 inches (1 cm) long of oligoclase, orthoclase, and quartz. In general it underlies the limestone.
The ores consist principally of the common sulfides and carbonates of copper.
Local structures include thrust and normal faulting, fracture zones, homoclinal. Regional trends include tilting and broad open folds in the south and extensive faulting in the north.
Workings include tunnel operations and cuts and are 914.4 meters long. Development totals some 3,000 feet of workings on 3 levels. Closed in 1902 due to low copper prices. Produced some 3,000 tons of ore averaging about 5% Cu and 1.5 oz. Ag/T from the late 1880's to 1902.
10 entries listed. 8 valid minerals.
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