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Walker Mine (Walker Brothers Mine; Walker Copper Mine; Native Son Mine [?]), Argentine Rock, Genesee Valley District (Genesee District), Plumas Copper Belt, Plumas Co., California, USA

Latitude: 39°57'37"N
Longitude: 120°40'3"W
A former lode Cu-Au-Ag-Zn-Pb mine located in secs. 5-8, T24N, R12E, and in secs. 29-32, T25N, R12E, MDM, 8.2 km (5.1 miles) E of Argentine Rock, 9.4 km (5.9 miles) NE of Greenhorn, about 2 miles SW of Mount Ingalls, about 8 miles SSE of Genesee, and 12 miles SE of Taylorville, in the headwaters area of Dolly Creek, on private property (patented claim). Land status: ownership category mixed. Owned by American Metals (1975); by AMAX, Inc. (50%), Nevada (1978); and the Continental Oil Co (CONOCO) (50%), Nevada (1978). Owned by the Calicopia Corp., Robert Barry, President, Beverly Hills, California (100.00%) (1978). Discovered in 1844 (MRDS file #10286027) or 1904 (MRDS file #10077104). Development did not begin until 1915. The mine was shut down 1932 - 1935. In 1935 it began treating 500 - 600 tons/day, which had increased by 1937 to 1200 tons/day. No known Pb or Zn were recovered. First year of production 1916. MRDS database stated accuracy for this location is 10 meters.

Mineralization is a vein deposit hosted in diorite, schist and hornfels. The ore body strikes N20-30W and dips 55-75E, at 15 meters thick, 36.58 meters wide and 304.8 meters long. It has a depth to, top, of 10 meters. It is a tabular/lenticular & massive-shaped replacement ore body with disseminated and massive ore. The primary mode of origin was contact metasomatism and the secondary mode was metamorphism. Primary ore control was lithology and folding was the secondary mode. Wallrock alteration is moderate including intermediate argillic and silicification. Chalcopyrite is the most prominent copper mineral in the ore. It carries considerable bornite, and in the richest streaks, pyrite is plentiful. Sphalerite, garnet, stibnite, cubanite, tetrahedrite, gold and jamesonite together comprise 0.59 weight percent of the total minerals present. Feldspar, biotite, pyroxene, actinolite, and tourmaline together comprise 5.0 weight percent of the total minerals present. The total mineral breakdown is as follows: 3.02 wt% chalcopyrite; 0.20 wt% chalcocite; 75.00 wt% quartz tourmaline; 2.50 wt% chlorite; 7.47 wt% magnetite, 0.98 wt% pyrite; 0.24 wt% pyrrhotite; 0.59 wt% sphalerite+galena+stibnite+cubanite+gold+tetrahedrite+jamesonite; 5.00 wt% feldspar+biotite+pyroxene+actinolite+tourmaline - 100.00 wt% total matrix. Local rocks include Mesozoic granitic rocks, unit 3 (Sierra Nevada, Death Valley area, Northern Mojave Desert and Transverse Ranges).

Local structures include faults with a maximum displacement of 20 feet, which cuts the veins. A quartz-diorite dike is found to displace the veins 10 feet.

The mine was discovered in 1909; mining efforts were not begun until 1911. Controlling interest in the mine was acquired by International Smelting and Refining Co, a subsidiary of Anaconda Copper Mining Co. By 1916 an extensive program of diamond drill coring proved enough ore on property to justify a flotation plant of 85 tons/day capacity; the plant was enlarged to handle 160 tons/day in 1918. The mine closed circa 1941.

The adjacent mining community established by Anaconda Copper was called Walkermine (one word) and is now demolished.

The oldest formation in the area is a pre-Silurian metarhyolite on Little Grizzly Creek. Overlying this are: the Peale Formation (Carboniferous), composed of sandstones, shales and some cherts; the Taylor meta-andesite; the Robinson Formation (Carboniferous, of sandstones and shales with few limestone lenses, and conglomerate beds; the Kettle meta-andesite; and the Trail Formation (Lower Jurassic), of slaty shales with some interbedded sandstones and conglomerates. These formations strike N30W in belts ½ to 1 mile wide, extending southeasterly from Genesee to the Walker Mine. The Trail Formation is altered in part to hornfels by intrusion of granodiorite. Alteration is intense. Little remains to indicate the original composition. The country rock is a fine-grained dark schist or hornfels formed by action of igneous intrusions on the sedimentary series.

Production data: continuous production from 1916-1932 was 2,876,000 metric tons mined. The period 1935-1941 continuous production realized 1,955,000 metric tons mined. Production data are found in: Averill (1937).

Bedrock sampling was conducted by the Bureau of Mines in 1978. There has been no mining activity at the Walker since 1978. In 1983; however, an unspecified company did some limited geological mapping. (John Burnett (1984), California Division of Mines and Geology, personal communication with the U.S. Bureau of Mines, WFOC, April 4, 1984.

Comments on the reserve resource information:

90% probability represents ore blocked out as of 1941 when production ceased - Anaconda company data. 75% probability represents combined probable and possible ore as proposed by Anaconda in 1941. 50% probability is assumed on the basis of favorable geologic conditions. Additional tonnages may be present based on exploration by CONOCO (Continental Oil Company) and American Metals Climax was conducted. Work was ongoing since 1975.

The mining method was filled stopes - horizontal cut and fill with tailings. Milling method was flotation.

Workings included extensive underground openings. They totaled 118,150 meters total length and an overall depth of 274.32 meters. An adit was 1,800 meters long.

The main haulage tunnel is the 7th level adit, 10,000 feet long. A raise was being driven from the Piute ore body to the surface in 1924. A winze had been sunk 500 feet on the South ore body, from the 7th level to the 10th level, and 150 feet of drifting done on the latter. A 350 foot winze was sunk on the C ore body from the 7th to the 9th level, 900 feet of drifting done here. On the 8th level, 600 feet of drifting was done on the S ore bnody and 400 feet on the C ore body. All stoping was above the 7th level.

Mineral List

Actinolite
Baryte
'Biotite'
Bornite
Chalcocite
Chalcopyrite
'Chlorite Group'
Cordierite
Cubanite
'Feldspar Group'
Galena
'Garnet'
Gold
Jamesonite
Magnetite
Pyrite
'Pyroxene Group'
Pyrrhotite
Quartz
Sphalerite
Stibnite
Tetrahedrite
'Tourmaline'


23 entries listed. 17 valid minerals.

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References

Hanks, Henry Garber (1884), Fourth report of the State Mineralogist: California Mining Bureau. Report 4, 410 pp. (includes catalog of minerals of California pp. 63-410), and miscellaneous observations on mineral products): 94.

Diller, J.S. (1905), Mineral resources of the Indian Valley region, California, USGS Bulletin 260: 45-49.

Diller, J.S. (1908), Geology of the Taylorsville region, California: USGS Bulletin 353: 115.

Turner, Henry Ward & A.F. Rogers (1914), A geologic and microscopic study of a magmatic copper sulphide deposit in Plumas County, California, and its modification by ascending secondary enrichment: Economic Geology: 9: 359-391.

Hamilton, Fletcher (1921) 17th Report of the State Mineralogist - Mining in California During 1920; California State Mining Bureau, January, 1921.

Logan, Clarence August (1921), Auburn field division: California Mining Bureau. Report 17: 471-473.

Young, George J. (1924), Anaconda's Walker Mine and Mill, Engineering and Mining Journal Press: 117(18): 725.

Averill, Charles V. (1928), Redding field division, Tehema and Plumas counties: California Division Mines & Mining Report 24: 280-285.

Knopf, Adolf (1935), Copper resources of the world; Plumas County copper belt, California: 16th. International Geol. Cong., I: 241-245.

Averill, Charles V. (1937), Mineral resources of Plumas County: California Journal of Mines and Geology, California Division Mines (Report 33): 33(2): 95-103, 113.

U.S. Bureau of Mines (1938), Copper Mining in North America, Bulletin 405: 61.

Eric, J.C. (1948), Copper in California: California Division of Mines Bulletin 144: 290.

Goodwin, Joseph Grant (1957) Lead and zinc in California. California Journal of Mines and Geology, Division of Mines: 53(3&4): 599.

Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 133, 163.

Smith, A.R. (1970) Trace elements in the Plumas Copper Belt, Plumas County, California. California Division of Mines and Geology Special Report 103: 3-26.

Wetzel, N. (1978), The Walker Copper Mine, Plumas County, Caifornia; U.S. Bureau of Mines MAS Report (July, 1978), 34 pp.

Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 69, 85, 88 (map 3-3), 90, 93, 95 (map 3-5), 103, 134, 150.

University of California, Berkeley (1988), Mining Waste Study, Final Report (July, 1988), 416 pp.: 231-235.

USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10286027 & 10077104.

U.S. Bureau of Mines, Minerals Availability System (MAS) file ID #0060630556.

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