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Quail Hill Mine (Eagle Mine; Eagle Copper and Silver Mine), Telegraph City, Foothill Copper Belt, Calaveras Co., California, USA

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A former Cu-Zn-Pb-Ag-Au mine located in the W½ & S½ sec. 3 & in sec. 10, T1N, R11E, MDM, 3.1 km (1.9 miles) NNW of Telegraph City, and about 10 km (6½ miles) WSW of Copperopolis, near the Stanislaus County line. Operated during the periods 1888 to 1916 and 1917 to 1945. MRDS database stated accuracy for this location is 100 meters.

Mineralization is a replacement deposit hosted in volcanic rock (aphanitic), greenstone and schist. The ore body is podiform/lenticular in form, strikes NW and dips 50-70NE, with a depth-to-top of 30.48 meters.

Regional grologic situation: Lower Sierra Nevada; thick sequence of lavas and pyroclastics and a variety of intrusive rocks. Both types of igneous rocks are in part metamorphosed to low-grade schsists and greenstones. The volcanics usually dip steeply NE and have a fairly constant NW strike. Schistosity, where developed, is generally parallel to the NW strike and NE dip. The largest intrusive is an irregular-shaped felsite body, 1,900 feet long and 1,500 feet wide. Dikes of greenishand diabase porphyry cutn the felsite intrusive and volcanic rocks.

The largest ore shoot, best exposed on the 205 level, widens downward below the 170 level, pinching out at the 240 level. This ore shoot parallels the adjacent hanging wall of the felsite intrusive. It dips toward the E and plunges 68SE, with a pitch length of 177 feet. Smaller ore shoots, similar in mode of occurrence, are spatially related to salients in the hanging wall of the felsite intrusive, or to faults, or to both. These shoots replaced intrusive felsite in shear zones. Local alteration includes sericitization, kaolinization, silicification, and pyritization. The most favorable ground is that lying along the trend of the downward extension of the strongly mineralized zone. Associated rocks include diabase. Local rocks include Mesozoic volcanic rocks, unit 2 (Western Sierra Foothills and Western Klamath Mountains).

Local geologic structures include folds and faults.

Workings include underground openings with an overall depth of 85.34 meters and comprised of a 2-compartment vertical shaft 280 feet deep with levels at 70, 170, 205, and 270 feet. Sub-levels exist at 190 and 296 feet, plus 1 adit. Mining is cvarried on in open stopes. Many portions of the mine are inaccessible due to caving.

Production: data are found in: Heyl, G.R. (1948): 114.

No production reported.

Analytical data results: Ore from the largest ore shoot gave: 5.58% Cu; 15.6% Zn; 0.40 ounce/ton Au; 6.51 ounces Ag/ton; and, 0.5 to 1.8% Pb.

Mineral List

14 entries listed. 12 valid minerals.

The above list contains all mineral locality references listed on This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


Mining and Scientific Press (1862), Summary of mining news, California [selected counties]: Mining and Scientific Press: 4(2): 5.

Silliman, Benjamin, Jr. (1867a), A notice of the peculiar mode of the occurrence of gold and silver in the foothills of the Sierra Nevada, and especially at Whiskey Hill, in Placer County, and Quail Hill, in Calaveras County, California: California Academy of Natural Sciences Proceedings: 3: 349-351; […American Journal of Science, 2nd. series: 45: 92-95 (1868)]: 351.

Cronise, T.F. (1868), The natural wealth of California, 696 pp. H.H. Bancroft Co., San Francisco: 592.

Aubury, Lewis E. (1908), The copper resources of California: California Mining Bureau. Bulletin 50: 145, Pl. 2.

Bradley, W.W. (1943), Thirty-ninth report of the State Mineralogist: California Division Mines (Report 39): 39(3): 314-315.

Bradley, W.W. (1943), Thirty-ninth report of the State Mineralogist: California Division Mines (Report 39): 39(4): Pl. 8.

Huttl, John B. (1944), Neglected copper-zinc belt revived under war demand: Engineering & Mining Journal: 145: 62.

Heyl, George Richard (1948c) The zinc-copper mines of the Quail Hill area, Calaveras County, California. California Division Mines Bulletin 144: 111-122, 222, Pl. 41.

California Division of Mines (1957), Economic Mineral Map of California No. 7.

Goodwin, Joseph Grant (1957) Lead and zinc in California. California Journal of Mines and Geology, Division of Mines (Report 53): 53(3&4): 436.

Clark, Wm. B. & P.A. Lydon (1962), Mines and mineral resources of Calaveras County, California: California Division of Mines & Geology County Report 2; [… Geological Society of America Proceedings, 1933: 312-313, 1934]: 31-32, Pl. D.

Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 96, 127, 128, 159, 293, 338.

Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 45, 82, 291.

USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10102614 & 10162975.

U.S. Bureau of Mines, Minerals Availability System (MAS) file ID #0060090147.

USGS Mineral Investigative Resources Map file MR-34.

USGS Mineral Investigative Resources map file MR-19.

USGS Strategic Minerals Investigation Preliminary Map 3-182.

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