This district is in southwestern Tuolumne County. It is in that portion of the Mother Lode belt that extends through the vicinity of southeast Jacksonville to the vicinity of Moccasin Creek. The Jamestown district is just to the north, the Big Oak Flat-Groveland district is to the east, and the Coulterville district is to the southeast.
Jacksonville, named for Colonel Alden Jackson-as was the town of Jackson in Amador County-was founded as a supply center in 1848. The placer deposits here were extremely rich, credited with a production of $9 million. Lode mining began in the district in the late 1850s. The Eagle-Shawmut mine was operated on a large scale from 1897 until 1942. The district was served for some years by the Hetch-Hetchy Railroad.
Geology and Ore Deposits
The deposits occur near or at the contact between serpentine on the west and slate and schist on the east interlayered with a number of narrow bands of greenstone. The are deposits consist chiefly of large but low-grade bodies of pyrite ankerite-quartz and mariposite-ankerite-quartz rock and numerous pyrite-quartz stringers. Most of the gold values are in the sulfides; there is not much free gold. The are zones were as much as 180 feet in thickness. There are several adjacent but relatively barren massive bull quartz veins. Mining extended to depths of 3000 feet. The are usually contained 1/7, ounce or less gold per ton; for years the mill heads at the Eagle-Shawmut mine averaged about $2.75 per ton.
Clio $100,000+, Eagle-Shawmut $7.4 million, Harriman $100,000+, Mammoth $100,000, Moccasin, Orcutt, Republican, Tarantula $100,000+, Wheeler.
Knopf, Adolph. 1929, The Mother lode system of California, Eagle-Shawmut and Clio mines: U.S. Geol. Survey Prof. Paper 157, pp. 79-83.
Logan, C.A., 1935, Mother Lode gold belt of California: Clio, Eagle-Shawmut and Harriman mines: California Div. Mines Bull. 108, pp. 159-160 and 162-165.
Ransome. F.L., 1900, Mother lode district folio: U.S. Geol. Survey Geol. Atlas of the U.S., folio 63, 11 pp.
Storms, W. H., 1900, EagleÂ·Shawmut mine: California Min. Bur. Bull. 18, pp. 132-133.
Tucker, W.B., 1916, Tuolumne County, EagleÂ·Shawmut mine: California Min. Bur. Rept. 14, pp. 146-147.
Turner, H.W., and Ransome, F.L., 1897, Sonora folio California: U.S. Geol. Survey Geol. Atlas of the U. S., folio 41. 7 pp.