Jim-Montana

Prospect, Inactive

Commodities and mineralogy

Main commodities Cu; Zn
Other commodities Ag; Pb
Ore minerals chalcopyrite; galena; sphalerite; tennantite

Geographic location

Quadrangle map, 1:250,000-scale CH
Quadrangle map, 1:63,360-scale D-4
Latitude 67.82
Longitude -148.91
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Jim-Montana property lies in the hills immediately south of the North Fork Chandalar River and approximately 8 miles south-southwest of Reds Lake. The reference point is located near the south-center of the Jim-Montana claim group (secs. 28, 33, T. 35 N., R. 6 W., of the Fairbanks Meridian) and is generally the same as loc. 34 in DeYoung (1978). The claims extend approximately a mile west-northwest and east-southeast from the reference point. The Jim-Montana [and IF(?)] property is west of and contiguous with the Mowgli-Sher Khan claim group (CH094), and together they form one large claim block. The location is accurate within a 1-mile radius.

Geologic setting

Geologic description

Early descriptions of this prospect indicated only the presence of disseminated chalcopyrite and sphalerite with minor galena, tennantite, and malachite stains in skarn in the Silurian/Devonian Skajit Limestone (Grybeck, 1977; DeYoung, 1978). Newberry and others (1986) included it in a group of skarn deposits that form a belt northwest of and related to the granitic rocks of the Devonian(?) Horace Mountain plutons. Many of these skarns exhibit both garnet and pyroxene prograde and epidote and actinolite retrograde mineral assemblages, and Newberry and others (1986) stated that the mineralogy, mineralization, and alteration of these skarns categorize them as continental-margin, porphyry-related copper skarns. Newberry and others (1986) classified the prospect, as a Cu-Zn-Pb prospect and Newberry and others (1997) suggest that these Pb-Zn-rich skarns represent distal concentrations surrounding porphyry systems in the Chandalar district. Newberry and others (1997) classify the Jim-Montana deposit as a calcic Zn-Pb skarn and replacement body. The country rock near this prospect is principally Devonian Skajit Limestone (Brosgé and Reiser, 1964).
Geologic map unit (-148.912764138391, 67.8196092988372)
Mineral deposit model Zn-Pb skarn deposits? (Cox and Singer, 1986; model 18c?).
Mineral deposit model number 18c?
Age of mineralization Devonian(?) based on reported Early Devonian Pb/Pb zircon ages from the associated Baby Creek batholith and Horace Mountain plutons (Dillon and others, 1996).
Alteration of deposit Calc-silicate(?).

Production and reserves

Workings or exploration Claims staked in 1972 and 1975.
Indication of production None

Additional comments

See also: Mowgli-Sher Khan prospect (CH094).
Alaska Kardex Nos. 031-58a, 031-60a (Kardex is a card file mining claim information system located at the State of Alaska DNR Public Information Center in Fairbanks).

References

MRDS Number A012143

References

Arctic Environmental Information and Data Center, 1982, Mineral terranes of Alaska: University of Alaska, Fairbanks, Arctic Environmental Information and Data Center, 7 sheets, scale 1:1,000,000.
Maas, K.M., 1987, Maps summarizing land availability for mineral exploration and development in northern Alaska, 1986: U.S. Bureau of Mines Open-File Report 10-87, 33 quadrangle overlays.
Newberry, R.J., Allegro, G.L., Cutler, S.E., Hagen-Levelle, D.D., Adams, D.D., Nicholson, L.C., Weglarz, T.B., Bakke, A.A., Clautice, K.H., Coulter, G.A., Ford, M.J., Myers, G.L., and Szumigala, D.J., 1997, Skarn deposits of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 355-395.
Newberry, R.J., Dillon, J.T., and Adams, D.D., 1986, Regionally metamorphosed calc-silicate-hosted deposits of the Brooks Range, northern Alaska: Economic Geology, v. 81, p. 1728-1752.
Reporters J.M. Britton (Anchorage)
Last report date 11/17/1999