Mikado mine (Mikado

Site Name

Primary: Mikado mine (Mikado
Secondary: Little Mikado
Secondary: Tobin
Secondary: Carter
Secondary: Eclipse
Secondary: Overlook
Secondary: Engineers Exploration Syndicate
Secondary: Idaho-Alaska Corp.)

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Commodity

Primary: Gold
Secondary: Antimony
Secondary: Lead
Secondary: Silver
Secondary: Arsenic
Secondary: Zinc

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Location

State: Alaska
District: Chandalar

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Land Status

Not available

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Holdings

Not available

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Workings

Not available

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Ownership

Not available

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Unknown
Years of Production:
Organization:
Significant:

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Physiography

Not available

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Mineral Deposit Model

Model Name: Low-sulfide Au-quartz vein

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Orebody

Not available

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Structure

Not available

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Alterations

Alteration Text: Oxidation of vein material produces scorodite and limonite.

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Rocks

Role: Host
Age Type: Host Rock
Age Young: Devonian

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Analytical Data

Not available

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Materials

Ore: Arsenopyrite
Ore: Galena
Ore: Gold
Ore: Pyrite
Ore: Siderite
Ore: Sphalerite
Ore: Stibnite
Gangue: Quartz

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Comments

Comment (Reserve-Resource): Reserves = Various reserve figures, which generally do not define reserves for specific deposits, have been published for the Chandalar area lode properties. Some of these figures are as follows: Bundtzen and others (1982) reported that in 1979 the Mikado property had proven reserves of 30,000 tons of 1 oz of gold per ton, and Nokleberg and others (1987) noted 12,000 tonnes grading 75 grams of gold per tonne at the Mikado and Little Squaw mines. An inferred lode reserve for the Chandalar district lodes of 45,000 tons with a grade of 2 oz of gold per ton was reported as late as 1997 (Swainbank and others, 1998). Heiner and Wolff (1968) reported proved reserves estimated to be $2,000,000 with the ore valued at $85 per ton. Baggs and others (1988) reported 13,600 metric tons of measured, 4,500 metric tons indicated and 18,200 metric tons inferred at a grade of 85.2 grams of gold per metric ton as of 1980.

Comment (Deposit): Model Name = Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)

Comment (Production): Production Notes = The amount of gold produced from the Mikado vein prior to 1960 is unknown; however, a small stamp mill was constructed on Spring Creek by 1913 to process ore from the Mikado and Little Squaw mines. Production between 1960 and 1979 was reported to be approximately 1,000 oz Au and 200 oz Ag (Cobb and Cruz, 1983). In 1979 the Little Squaw Gold Mining Co. resumed development and seasonal production, and the ore was processed through a cyanide leach-flotation plant on Tobin Creek at a rate of 100 to 125 tons per day (Bundtzen and others, 1984). Production during 1981 was reported as 4,000 tons of ore worth $1.6 million (Bundtzen and others, 1982). In 1983 it was estimated that 10,000 oz of gold had been recovered during the last several years (1979-1982?) (Bundtzen and others, 1984). Lode production apparently ceased in 1983 due to lack of developed reserves and the high cost of the remote operations.

Comment (Geology): Age = Middle Cretaceous based on arguments by Dillon (1982) that the age of emplacement of the gold-bearing quartz veins of the Koyukuk and Chandalar districts was between the Neocomian metamorphism of the Devonian host rocks and their erosional unroofing and cooling in Albian time.

Comment (Workings): Workings / Exploration = Maddren (1913) reported open cuts that exposed auriferous quartz in six places over a strike length of 3,000 feet. Underground workings, including a 100-foot shaft and 160-foot adit, reportedly were completed by 1913. The underground workings were reopened in 1960, and an additional 600 feet of new workings were driven. An additional 800 feet was driven in 1962-63. An unknown amount of work was done in late 1960s, and again in the late 1970s and early 1980s (Bundtzen and others, 1982). Some bulldozer trenching was completed on veins in the area in 1962.

Comment (Geology): Geologic Description = Discovered in 1909, the Mikado vein is one of several auriferous quartz veins in an area approximately 1 mile wide and 2 1/2 miles long between the heads of Tobin and Big creeks to the south and Squaw and Little Squaw creeks to the north. In general, most of the gold-bearing quartz veins in this area are in or near steeply dipping, northwest-trending normal faults in Devonian quartz-muscovite schist, phyllite, and quartzite intruded by Devonian mafic sills and dikes (Chipp, 1970). The intrusions have been metamorphosed to greenstone or greenschist. Major structural features include large-scale northeast-trending anticlines and synclines, northeast-trending thrusts, and the northwest-trending, high-angle cross faults. The Mikado vein/fault system is described as a shear zone about 50 feet wide which contains sub-parallel, highly faulted and brecciated, steeply dipping (80 N), auriferous quartz veins up to 6 feet thick which have been exposed for over 3,000 feet along the Mikado fault (Maddren, 1913). Although the Mikado vein is said to average 6 feet in thickness over a 500-feet strike length, most of the ore shoots are discontinuous and generally are a few tens or hundreds of feet long. According to Boadway (1933), the Mikado vein in the underground workings consists of lenses of auriferous quartz, mostly on the hangingwall side of a gouge-filled fault. The vein appears to be approximately 35 inches or less in width in the upper levels and narrows to 16 inches at a depth of 99 feet. Ore shoots in the vein reportedly assayed from $37 per ton to as high as $439 per ton at $20 per ounce of gold), and one ore shoot averaged $49.50 per ton over a 35-inch width (Chipp, 1970). Drilling has intersected additional quartz in both the hangingwall and footwall of the fault. In a general description of the Chandalar gold-quartz lodes, Chipp (1970) indicated that white, crystalline to microcrystalline quartz is the dominant gangue mineral and that crystals of quartz are commonly found in small vugs. Banding in the quartz veins is produced by shearing and by elongated cavities in the veins parallel to the walls. Siderite occurs in minor amounts. Ashworth (1983) described three generations of quartz in the Mikado deposit: (1) lenses and pods of quartz plus or minus pyrite plus or minus dolomite, which are possibly pre-faulting metamorphic segregations; (2) massive, white, coarsely crystalline quartz with less than 5 percent sulfides and trace gold; and (3) 'main stage' quartz, which is fine grained, white, and in places vuggy. The sulfide assemblage in main stage quartz consists in decreasing order of abundance of arsenopyrite, galena, sphalerite, stibnite, and pyrite. Native gold, as flakes or wires, is common in the Mikado and typically is along the borders of sulfide grains or in quartz near sulfides. Sulfides generally form less than 5 percent of the veins. Early workers postulated the source of the gold-quartz mineralization to be small granitic intrusives, based largely on the presence of monazite and rutile in the placers (Mertie, 1925). Chipp (1970) suggested that there may be a genetic relationship with the the larger greenstone bodies as well. The genesis of these gold deposits is still in question, although various workers have hypothesized some genetic link to a variety of felsic and mafic igneous rocks from which the gold was remobilized during metamorphism (Mertie, 1925; Boadway, 1933; Chipp, 1970; Dillon, 1982).

Comment (Reference): Primary Reference = Chipp, 1970; Ashworth, 1983

Comment (Deposit): Other Comments = There has been active exploration and small production up to the present. Recent literature, and especially news notes, may confuse the Little Squaw and Mikado mines because the Mikado is owned by Little Squaw Mining Co. References to the Little Squaw property thus may refer to either the Little Squaw Mine, the Mikado mine, or both. The names Idaho-Alaska Corp. and Engineers Exploration Syndicate associated with this property refer to the transaction in 1932 in which the Idaho-Alaska Corp. took over the leases and options formerly held by the Engineers Exploration Syndicate on various properties in the Chandalar district.

Comment (Exploration): Status = Inactive

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References

Reference (Deposit): Bundtzen, T.K., Swainbank, R.C., Wood, J.E., Clough, A.H., 1991 (1992), Alaska's Mineral Industry 1991: Alaska Division of Geological & Geophysical Surveys, Special Report 46, 89 p.

Reference (Deposit): Williams, J.A., 1960, Report of the Division of Mines and Minerals for the year 1960: Alaska Territorial Department of Mines Annual Report 1960, 88 p.

Reference (Deposit): Nokleberg, W.J., Bundtzen, T.K., Dawson, K.M., Eremin, R.A., Goryachev, N.A., Koch, R.D., Ratkin, V.V, Rozenblum, I.S., Shpikerman, V.I., Frolov, Y.F., Gorodinsky, M.E., Melnikov, V.D., Diggles, M.F., Ognyanov, N.V., Petrachenko, E.D., Petrochenko, R.I., Pozdeev, A.I., Ross, K.V., Wood, D.H., Grybeck, D., Khanchuck, A.I., Kovbas, L.I., Nekrasov, I.Y., and Sidorov, A.A., 1996, Significant metalliferous and selected non-metalliferous lode mineral deposits and placer districts, and for metallogenesis of the Russian Far East, Alaska, and the Canadian Cordillera: U.S. Geological Survey Open-File Report 96-513-B, 385 p.; U.S. Geological Survey Open-File Report 96-513-B, 385 p. (CD-ROM format).

Reference (Deposit): Reed, I.M., 1930, Report on the Little Squaw area of the Chandalar mining district: Alaska Territorial Department of Mines Miscellaneous Report 31-4, 18 p.

Reference (Deposit): Bundtzen, T.K., Green, C.B., Deagen, J., and Daniels, C.L., 1987, Alaska's mineral industry, 1986: Alaska Division of Geological and Geophysical Surveys, Special Report 40, 68 p.

Reference (Deposit): Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck, D.J., Robinson, M.S., Smith, T.E., and Yeend, W., 1987, Significant metalliferous lode deposits and placer districts of Alaska: U.S. Geological Survey Bulletin 1786, 104 p.

Reference (Deposit): Baggs, D.W., Northam, M.J., Meyer, M.P., and Maas, K.M., 1988, Selected significant mineral deposits in Alaska, a minerals availability system overview: U.S. Bureau of Mines Information Circular 9177, 124 p.

Reference (Deposit): Bundtzen, T.K., Green, C.B., Peterson, R.J., and Seward, A.F., 1988, Alaska's mineral industry, 1987: Alaska Division of Geological and Geophysical Surveys Special Report 41, 69 p.

Reference (Deposit): Eakins, G.R., Bundtzen, T.K., Lueck, L.L. Green, C.B., Gallagher, J.L., and Robinson, M.S., 1985, Alaska mineral industry, 1984: Alaska Division of Geological and Geophysical Surveys Special Report 38, 57p.

Reference (Deposit): Eakins, G.R., Bundtzen, T.K., Robinson, M.S., Clough, J.G., Green, C.B., Clautice, K.H., and Albanese M.A., 1983, Alaska's mineral industry, 1982, Alaska Division of Geological and Geophysical Surveys Special Report 31, 63 p.

Reference (Deposit): Bundtzen, T.K., Eakins, G.R., Clough, J.G., Lueck, L.L., Green, C.B., Robinson, M.S., and Coleman, D.A., 1984, Alaska's Mineral Industry, 1983: Alaska Division of Geological and Geophysical Surveys Special Report 33, 56 p.

Reference (Deposit): Heiner, L.E., and Wolff, E.N., eds., 1968, Mineral resources of northern Alaska, Final report, submitted to the NORTH Commission: Mineral Industry Research Laboratory, University of Alaska, Report 16, 306 p.

Reference (Deposit): Ashworth, K.K., 1983, Genesis of gold deposits at the Little Squaw mines, Chandalar mining district, Alaska: Bellingham, Washington, Western Washington University, M.Sc. thesis, 98 p.

Reference (Deposit): Saunders, R.H., 1959, Silver-lead occurrences in the Fairbanks district: Alaska Territorial Department of Mines Miscellaneous Report 194-18, 19 p., 2 maps, scale 1:63,360.

Reference (Deposit): Cobb, E.H., and Cruz, E.L., 1983, Summaries of data and lists of references to metallic and selected nonmetallic mineral deposits in the Chandalar quadrangle, Alaska: U.S. Geological Survey Open-File Report 83-278, 91 p.

Reference (Deposit): Saunders, R.H., 1962, Report on exploration in the Chandalar district: Alaska Territorial Department of Mines Prospect Evaluation 31-3, 5 p.

Reference (Deposit): Reiser, H.N., Brosgi, W.P., De Young, J.H., Jr., Marsh, S.P., Hamilton, T.D., Cady, J.W., and Albert, N.R.D., 1979, The Alaskan Mineral Resource Assessment Program: Guide to information contained in the folio of geologic and mineral resource maps of the Chandalar quadrangle, Alaska: U.S. Geological Survey Circular 758, 23 p.

Reference (Deposit): Bundtzen, T.K., Eakins, G.R., and Conwell, C.N., 1982, Review of Alaska mineral resources 1981: Alaska Division of Geological and Geophysical Surveys Annual Report 1981, 48 p., 2 sheets, scale 1:3,000,000.

Reference (Deposit): Anderson, Eskil, 1944, Petrographic descriptions of rocks collected during 1944 field investigation in north-west Alaska, and lists of ore and rock samples and placer concentrates collected in northwestern and interior Alaska during 1945 field season: Alaska Territorial Department of Mines Miscellaneous Report 195-28, 76 p.

Reference (Deposit): Dillon, J.T., 1982, Source of lode and placer gold deposits of the Chandalar and upper Koyukuk Districts: Alaska Division of Geological and Geophysical Surveys Open-File Report 158, 25 p., 1 sheet, scale 1:250,000.

Reference (Deposit): Bundtzen, T.K., Eakins, G.R., and Conwell, C.N., 1982, Alaska mineral resources 1981-82: Alaska Division of Geological and Geophysical Surveys Annual Report 1981-82, 153 p., 4 sheets, scale 1:2,500,000.

Reference (Deposit): DeYoung, J.H., Jr., 1978, Mineral resources map of the Chandalar quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-878-B, 2 sheets, scale 1:250,000.

Reference (Deposit): Cobb, E.H., 1973, Placer deposits of Alaska: U.S. Geological Survey Bulletin 1374, 213 p.

Reference (Deposit): Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Chandalar and Wiseman quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-340, 205 p.

Reference (Deposit): Grybeck, D.J., 1977, Known mineral deposits of the Brooks Range, Alaska: US Geological Survey Open-File Report 77-166C, 41 p., 1 sheet, scale 1:1,000,000.

Reference (Deposit): Chipp, E.R., 1970, Geology and geochemistry of the Chandalar area, Brooks Range, Alaska: Alaska Division of Geological and Geophysical Surveys Geologic Report 42, 39 p., 1 sheet, scale 1:36,000.

Reference (Deposit): Brosgi, W.P., and Reiser, H.N., 1972, Geochemical reconnaissance in the Wiseman and Chandalar districts and adjacent region, southern Brooks Range, Alaska: U.S. Geological Survey Professional Paper 709, 21 p.

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Chandalar quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-457, 1 sheet, scale 1:250,000.

Reference (Deposit): Boadway, E.A., 1933, Report on Mikado and Little Squaw veins, Chandalar, Alaska: Alaska Territorial Department of Mines Miscellaneous Report 31-7, 37 p.

Reference (Deposit): Smith, P.S., 1934, Mineral industry of Alaska in 1932: U.S. Geological Survey Bulletin 857-A, p. 1-91.

Reference (Deposit): Boadway, E.A., 1932, Report on Sulzer properties, Chandalar, Alaska: Alaska Territorial Department of Mines Miscellaneous Report 31-6, 23 p., 4 sheets.

Reference (Deposit): Stanford, J.V., 1931, Report on Little Squaw, Bonanza, and Mikado groups of claims, Chandalar, Alaska: Alaska Territorial Department of Mines Miscellaneous Report 31-5, 10 p.

Reference (Deposit): Reed, I.M., 1927, Report on some of the quartz prospects of the Chandalar district: Alaska Territorial Department of Mines Miscellaneous Report 31-2, 4 p.

Reference (Deposit): Brooks, A.H., 1914, Mineral resources of Alaska in 1913: U.S. Geological Survey Bulletin 592, p. 340-341.

Reference (Deposit): Mertie, J.B., Jr., 1925, Geology and gold placers of the Chandalar district, in Brooks, A.H., and others, Mineral resources of Alaska, report on progress of investigations in 1923: U.S. Geological Survey Bulletin 773, p. 215-263.

Reference (Deposit): Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck, Donald, Robinson, M.S., Smith, T.E., and Yeend, Warren, 1988, Metallogeny and major mineral deposits of Alaska: U.S. Geological Survey Open-File Report 88-73, 97 p., 2 plates, scale 1:5,000,000.

Reference (Deposit): Nokleberg, W.J., Bundtzen, T.K., Grybeck, D.J., Koch, R.D., Eremin, R.A., Rozenblum, I. S., Sidorov, A.A., Byalobzhesky, S.G., Sosunov, G.M., Shpikerman, V.I., Gorodinsky, M.E., 1993, Metallogenesis of mainland Alaska and the Russian Northeast: U.S. Geological Survey Open-File Report 93-0339, 3 sheets, 230 p.

Reference (Deposit): Thompson, G.L., 1925, Report on the property of the Chandalar Gold Company: Alaska Territorial Department of Mines Miscellaneous Report 31-1, 18 p.

Reference (Deposit): Maddren, A.G., 1913, The Koyukuk-Chandalar region, Alaska: U.S. Geological Survey Bulletin 532, 119 p.

Reference (Deposit): Swainbank, R.C., Clautice, K.C., and Nauman, J.L., 1998, Alaska's Mineral Industry 1997: Alaska Division of Geological and Geophysical Surveys Special Report 52, 65 p.

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