Red Top

Site Name

Primary: Red Top

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Commodity

Primary: Mercury

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Location

State: Alaska
District: Bristol Bay region

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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: Disseminated epithermal mercury antomony

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Orebody

Not available

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Structure

Not available

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Alterations

Alteration Type: L
Alteration Text: Hematite and limonite, closely associated with cinnabar and dickite, line the walls of some veins.

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Rocks

Role: Host
Age Type: Host Rock
Age Young: Jurassic

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Analytical Data

Not available

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Materials

Ore: Cinnabar
Gangue: Quartz
Gangue: Limonite
Gangue: Hematite
Gangue: Dolomite
Gangue: Dickite
Gangue: Calcite

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Comments

Comment (Geology): Age = Late Cretaceous or Tertiary. The Red Top deposit postdates regional deformation of the host Jurassic sedimentary rocks and is probably similar in age to other mercury deposits of southwest Alaska that postdate regional deformation of Cretaceous sedimentary rocks.

Comment (Reference): Primary Reference = Sainsbury and MacKevett, 1965

Comment (Workings): Workings / Exploration = Placer cinnabar was discovered in 1941in Arcana Creek, which drains eastward from the center of Marsh Mountain; follow-up exploration the next year discovered the lode deposits of the Red Top mine (Sainsbury and MacKevett, 1965, p. 57). The U. S. Defense Minerals Exploration Administration funded 10,000 feet of surface dozer trenching in 1952 and the driving of a upper adit and drifts totaling 560 feet of underground workings in 1955. Subsequently, a lower adit and drifts totaling about 920 feet of underground workings was driven by mining companies. Exploration drilling was completed from the lower adit workings in 1958. C. L. Sainsbury mapped the surface and underground workings in 1959 (Sainsbury and MacKevett, 1965, p. 57).

Comment (Production): Production Notes = Surface trenching exposed ore from which 22 flasks of mercury were recovered and a total of 60 flasks of mercury were recovered by 1959. In 1959, the amount of stockpiled ore was estimated to contain at least another 60 flasks of recoverable mercury (Sainsbury and MacKevett, 1965, p. 58). Although Pennington (1959) reported that exploration had found ore that contained an estimated 1,400 flasks of mercury, production for the Red Top mine probably totals about 100 flasks of mercury.

Comment (Geology): Age = Host rock is Jurassic.

Comment (Exploration): Status = Probably inactive

Comment (Deposit): Model Name = Cinnabar vein and breccia deposits (Cox and Singer, 1986; model 27?)

Comment (Geology): Geologic Description = Placer cinnabar was discovered in 1941 in Arcana Creek, which drains eastward from the center of Marsh Mountain; follow-up exploration the next year discovered the lode deposits of the Red Top mine (Sainsbury and MacKevett, 1965, p. 57). The U. S. Defense Minerals Exploration Administration funded 10,000 feet of surface dozer trenching in 1952 and the driving of an upper adit and drifts totaling 560 feet of underground workings in 1955. Subsequently, a lower adit and drifts totaling about 920 feet of underground workings were driven by mining companies. Exploration drilling was completed from the lower adit workings in 1958. C. L. Sainsbury mapped the surface and underground workings in 1959 (Sainsbury and MacKevett, 1965, p. 57). Surface trenching exposed ore from which 22 flasks of mercury were recovered, and a total of 60 flasks of mercury were recovered by 1959. In 1959, the amount of stockpiled ore was estimated to contain at least another 60 flasks of recoverable mercury (Sainsbury and MacKevett, 1965, p. 58). Although Pennington (1959) reported that exploration had found ore that contained an estimated 1,400 flasks of mercury, production for the Red Top mine probably totals about 100 flasks of mercury.? the host rocks for the Red Top cinnabar deposits are interbedded, very fine- to very coarse-grained graywacke, calcareous graywacke, and siltstone. These rocks are probably correlative with Jurassic clastic sedimentary rocks like those in the southeast part of the Hagemeister Island quadrangle (Jk unit of Hoare and Coonrad, 1978; Decker and others, 1994, figure 1). Individual beds vary from a few inches to several feet or more in thickness. The beds generally strike east to northeast and in the area of the mine are folded broadly into a south-plunging syncline.? the principal controls on cinnabar mineralization are faults that fracture and brecciate massive graywacke. Faults in siltstone tend to be gouge-filled and tight; they commonly are not hosts for cinnabar deposits. The principal fault in the Red Top mine strikes west to northwest and dips 45 to 80 degrees south. This arcuate reverse fault has had consistent right-lateral oblique slip, including some displacements that postdate mineralization. It has been traced over a distance of about 1,250 feet at the surface and over 400 feet in the subsurface. Smaller subparallel faults and splays, generally striking west-northwest and dipping 40 to 50 degrees south, have also been mapped in the subsurface, particularly in the hanging wall of the main fault (Sainsbury and MacKevett, 1965, plate 7).? Cinnabar, the only sulfide mineral identified in the Red Top mine, occurs in discrete small veins up to 4 inches wide that have been traced laterally up to 200 feet but are commonly a few tens of feet long. Cinnabar also occurs as disseminations in fractured graywacke and in the carbonate gangue that cements graywacke breccia; as replacements of graywacke fragments and

Comment (Geology): Geologic Description = dolomite in breccia; and as breccia fragments in or along massive carbonate pods. Dolomite or ankeritic dolomite and later calcite are the most common gangue minerals. The carbonate minerals occur as discontinuous pods and lenses along the faults and as cement in breccia. Other gangue minerals include hematite, limonite, scarce quartz, and fairly common dickite (Sainsbury and MacKevett, 1965, p. 61). The grade of mineralization is highly variable. Production has been from selected high-grade material. A sample of muck from a lower adit drift assayed 0.59 percent Hg, and a large grab sample from the lower adit dump assayed 1.09 percent Hg (Sainsbury and MacKevett, 1965, p. 64). Two cinnabar-rich samples from the Red Top mine contained less than 10 ppb Au and 150 and 7,000 ppm Sb (Hawley and others, 1969).? Surface sampling of soils and nearby stream sediments suggests that the area surrounding the Red Top mine on Marsh Mountain may contain other occurrences of mercury mineralization (Eakin, 1968). Cinnabar reported from Wood River gravels (Malone, 1962, p. 57) could have been derived from the area of the Red Top mine.

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References

Reference (Deposit): Malone, Kevin, 1962, Mercury occurrences in Alaska: U.S. Bureau of Mines Circular 8131, 57 p.

Reference (Deposit): Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Dillingham, Sleetmute, and Taylor Mountains quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-606, 92 p.

Reference (Deposit): Sainsbury, C.L. and MacKevett, E.M., Jr., 1965, Quicksilver deposits of southwestern Alaska: U.S. Geological Survey Bulletin 1187, 89 p.

Reference (Deposit): Hawley, C.C., Martinez, E.E., and Marinenko, John, 1969, Geochemical data on the South ore zone, White Mountain mine, and on the gold content of other mercury ores, southwestern Alaska, in Some shorter mineral resources investigations in Alaska: U.S. Geological Survey Circular 615, p. 16-20.

Reference (Deposit): Pennington, J.W., 1959, Mercury. A materials survey, with a chapter on resources by Edgar H. Bailey: U.S. Bureau of Mines Information Circular 7941, 92 p.

Reference (Deposit): Decker, J., Bergman, S.C., Blodgett, R.B., Box, S.E., Bundtzen, T.K., Clough, J.G., Coonrad, W.L., Gilbert, W.G., Miller, M.L., Murphy, J.M., Robinson, M.S., and Wallace, W.K., 1994, Geology of southwestern Alaska, in Plafker, G. and Berg, H.C., eds., The Geology of Alaska: Boulder, Colorado, Geological Society of America, The Geology of North America, v. G-1, p. 285-310.

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Dillingham quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-375, 1 sheet, scale 1:250,000.

Reference (Deposit): Hoare, J.M., and Coonrad, W.L., 1978, Geologic map of the Goodnews and Hagemeister Island quadrangles region, southwestern Alaska: U.S. Geological Survey Open-File Report 78-9-B, two sheets, scale 1:250,000.

Reference (Deposit): Eakins, G.R., 1968, A geochemical investigation of the Wood River-Tikchik area, southwestern Alaska: Alaska Division of Mines and Minerals, Geochemical Report 17, 31 p.

Reference (Deposit): Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Dillingham, Sleetmute, and Taylor Mountain quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-606, 92 p.

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