Red Top

Mine, Undetermined

Commodities and mineralogy

Main commodities Hg
Ore minerals cinnabar
Gangue minerals calcite; dickite; dolomite; hematite; limonite; quartz

Geographic location

Quadrangle map, 1:250,000-scale DI
Quadrangle map, 1:63,360-scale B-7
Latitude 59.2751
Longitude -158.5342
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Red Top Mine is near the top of the southeastern peak of Marsh Mountain; the mine is plotted on the USGS B-7, 1:63,360-scale topographic map. It is at an elevation of about 1,100 feet, about 3.1 miles east of the village of Aleknagik, and about 0.6 mile south-southwest of the center of section 27, T. 10 S., R. 54 W. The location is accurate.

Geologic setting

Geologic description

Placer cinnabar was discovered in 1941 in Arcana Creek, which drains east 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). The U.S. Defense Minerals Exploration Administration funded 10,000 feet of surface dozer trenching in 1952 and about 560 feet of underground workings in an adit and drifts in 1955. Subsequently, a lower adit and drifts totaling about 920 feet of underground workings were driven by mining companies. There was considerable drilling underground in the workings of the lower adit in 1958. C.L. Sainsbury mapped the surface and underground workings in 1959 (Sainsbury and MacKevett, 1965). Twenty-two flasks of mercury were produced from ore mined in the trenches and a total of 60 flasks of mercury were recovered by 1959. In 1959, the stockpiled ore was estimated to contain at least another 60 flasks of recoverable mercury (Sainsbury and MacKevett, 1965). Although Pennington (1959) reported that exploration had found ore that contained an estimated 1,400 flasks of mercury, production from the Red Top mine probably totaled about 100 flasks of mercury to the mid-1960s.
In 1969, Clayton Rasmusson leased the property and brought in a 20-ton mill (D.J. Grybeck, unpublished field notes, 1970). A 'raise', actually an irregular stope, was driven at the end of the lower adit from one of the better zones of mineralization. About 100 tons of ore was stockpiled that Rasmusson estimated to contain about one-half percent mercury. Some of the ore was concentrated at the mill and 3 flasks of mercury were retorted from it in Anchorage. Rasmussen estimated that the total production to 1970 was about 120 flasks of mercury. Apparently, there has been little work since 1971.
The host rocks for the Red Top cinnabar deposit are interbedded, very fine- to very coarse-grained graywacke, calcareous graywacke, and siltstone. Wilson and others (2006) include them in their 'Graywacke of Kululak Bay' unit of Middle and Upper Jurassic age. Individual beds vary from a few inches to several feet or more in thickness. The beds generally strike east to northeast and the rocks near the mine are broadly folded into a south-plunging syncline.
The principal controls on cinnabar mineralization are faults and breccia zones in 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 for a distance of about 1,250 feet at the surface and for 400 feet in the subsurface. Smaller subparallel faults and splays, generally striking west-northwest and dipping 40 to 50 degrees south, have been mapped in the subsurface, particularly in the hanging wall of the main fault (Sainsbury and MacKevett, 1965).
Cinnabar, the only sulfide mineral identified in the Red Top Mine, occurs in discrete small veins up to 4 inches thick that have been traced laterally up to 200 feet but are commonly only 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 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). The grade of mineralization varies greatly. 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). Two cinnabar-rich samples from the Red Top Mine contained less than 10 parts per billion gold Au and 150 and 7,000 parts per million antimony (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 (Eakins, 1968). Cinnabar reported from Wood River gravels in the vicinity could have been derived from the Red Top deposit (Malone, 1962).
Geologic map unit (-158.536399730828, 59.2743575989058)
Mineral deposit model Cinnabar vein and breccia deposits (Cox and Singer, 1986; model 27b).
Mineral deposit model number 27b
Age of mineralization 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.
Alteration of deposit Hematite and limonite, closely associated with cinnabar and dickite, line the walls of some veins.

Production and reserves

Workings or exploration
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 that became the Red Top Mine (Sainsbury and MacKevett, 1965). 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).
In 1969, Clayton Rasmusson leased the property, revitalized the camp, and brought in a 20-ton mill (D.J. Grybeck, unpublished field notes, 1970). A 'raise', actually a irregular stope, was driven at the end of the lower adit from one of the better zones of mineralization. About 100 tons of ore was stockpiled that Rasmusson estimated to contain about 1/2-percent mercury. Some of the ore was concentrated at the mill and 3 flasks of mercury were retorted from it in Anchorage.
Indication of production Yes; small
Reserve estimates Pennington (1959) suggested that the Red Top Mine contained 1,4000 flasks of mercury. Three flasks were produced in the early 1970's but there has been no production since 1971.
Production notes Surface trenching exposed ore from which 22 flasks of mercury were recovered and a total of 60 flasks of mercury were recovered from surface and underground workings by 1959. In 1959, the stockpiled ore was estimated to contain at least another 60 flasks of mercury (Sainsbury and MacKevett, 1965). Although Pennington (1959) reported that exploration had found ore that contained an estimated 1,400 flasks of mercury. Clay Rasmussen (personal communication, 1970) estimated that the total production to 1970 was about 120 flasks of mercury. Apparently, there has been no production since 1971.

References

MRDS Number A013220
Reporters Travis L. Hudson (Applied Geology); D.J. Grybeck (Contractor, U.S. Geological Survey)
Last report date 4/2/2010