|Quadrangle map, 1:250,000-scale||TN|
|Quadrangle map, 1:63,360-scale||B-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Little Minook Jr. Creek placer mine is in section 9, T. 7 N., R. 12 W., of the Fairbanks Meridian. According to Cobb (1972, location 49), the mine workings are at least a mile long, near the headwaters of the creek. The site is at the cabin and mine symbol near the head of the creek. This site roughly corresponds with the site for Little Minook Jr. Creek, U.S. Bureau of Land Management MAS number 0020480075.|
Bedrock in the area of Little Minook Jr. Creek consists of gabbro, mafic volcanic and volcaniclastic rocks, argillite, chert, and limestone of the Triassic Rampart Group (Chapman and others, 1982; Reifenstuhl and others, 1997 [RI 97-15a]). The drainage area of the creek includes the Tertiary, gravel-covered California and Idaho bars, and the placer deposit is along the contact between Rampart Group rocks and the Tertiary gravels (Reifenstuhl and others, 1997 [RI 97-15a]).
The gold is mainly in the present stream channel, but some is also in local benches. On one claim, the upper 1.5 feet of irregular greenstone bedrock surface contained most of the gold. Overlying this pay streak was 4 to 5 feet of frozen gravel, overlain in turn by 18 to 25 feet of frozen muck and slide rock (Mertie, 1934). The stream gradient is 385 feet per mile.
The gold is flattened, suggesting that it probably was reconcentrated from bench placers (Hess, 1908). According to Mertie (1934), the gold is of comparable fineness to that of Little Minook Creek (TN066). The largest nugget was worth $200 (gold at $18 per ounce). Heavy-mineral concentrates contained pyrite, hematite, ilmenite, barite, magnetite, and galena (Waters, 1934).
Both drifting and surface mining techniques have been used in Little Minook Jr. Creek. Excess water hampered the drift mining, and a meager summer water supply hampered washing (Mertie, 1934). Mining reportedly was continuous on Little Minook Jr. Creek until 1935 (Smith, 1937; Cobb, 1977). In 1957, Saunders (1957 [MR 194-17]) reported that the Weisner Trading Company intended to mine on Little Minook Jr. Creek during that year and implied that mining had occurred on the creek in the recent past. Reports of more recent work are incomplete. Fairbanks Mining Company mined for 90 days in 1997 using a JD450 tractor and backhoe (Alaska Kardex files).
As of 1904, Little Minook Jr. Creek had produced a total of $150,000 worth of gold (Hess, 1908), equivalent to approximately 7,250 ounces of gold (at $20.67 per ounce). Production since then has not been made public.Six placer gold grains from Little Minook Jr. Creek were analyzed by electron microprobe (Newberry and Clautice, 1997). They found three different composition populations, but all grains examined exhibited evidence for extensive leaching. Several grains contained native nickel inclusions.
|Geologic map unit||(-150.043408393666, 65.4467210277817)|
|Mineral deposit model||Placer Au (Cox and Singer, 1986; model 39a).|
|Mineral deposit model number||39a|
|Age of mineralization||Quaternary.|
|Workings or exploration||Placer mining on Little Minook Jr. Creek was first reported by Prindle and Hess (1905; Cobb, 1977). Mining appears to have been continuous through 1913, and after an apparent hiatus, again in the early 1930s. Miners used both surface and drift mining techniques (Mertie, 1934). In 1957, Saunders (1957 [MR 194-17]) reported that the Weisner Trading Company intended to mine on Little Minook Jr. Creek during that year and implied that mining had occurred on the creek in the recent past. Reports of more recent work are incomplete. Fairbanks Mining Company mined for 90 days in 1997 using a JD450 tractor and backhoe (Alaska Kardex files).|
|Indication of production||Yes; small|
|Production notes||Hess (1908) reported total production through the fall of 1904 to be $150,000, equivalent to approximately 7,250 ounces of gold at $20.67 per ounce.|
Chapman, R.M., Yeend, W.E., Brosge, W.P., and Reiser, H.N., 1982, Reconnaissance geologic map of the Tanana quadrangle: U.S. Geological Survey Open-File Report 82-734, 20 p., scale 1:250,000.
Cobb, E.H., 1972, Metallic mineral resources map of the Tanana quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-371, 1 sheet, scale 1:250,000.
Cobb, E.H., 1977, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Tanana quadrangle, Alaska: U.S. Geological Survey Open-File Report 77-432, 98 p.
Hess, F.L., 1908, The Rampart placers, in Prindle, L.M., The Fairbanks and Rampart quadrangles, Alaska: U.S. Geological Survey Bulletin 337, p. 64-98.
Mertie, J.B., Jr., 1934, Mineral deposits of the Rampart and Hot Springs districts, Alaska: U.S. Geological Survey Bulletin 844-D, p. 163-226.
Newberry, R.J. and Clautice, K.H., 1997, Compositions of placer gold in the Rampart-Eureka-Manley-Tofty area, eastern Tanana and western Livengood quadrangles, central Interior Alaska, determined by electron microprobe analysis: Alaska Division of Geological and Geophysical Surveys Public Data File 97-49, 49 p.
Prindle, L.M., and Hess, F.L., 1905, Rampart placer region: U.S. Geological Survey Bulletin 259, p. 104-119.
Reifenstuhl, R.R., Dover, J.H., Pinney, D.S., Newberry, R.J., Clautice, K.H., Liss, S.A., Blodgett, R.B., Bundtzen, T.K., and Weber, F.R., 1997, Geologic map of the Tanana B-1 Quadrangle, central Alaska: Alaska Division of Geological & Geophysical Surveys Report of Investigation 97-15A, 17 p., 1 sheet, scale 1:63,360.
Saunders, R.H., 1957, Mining operations in the Rampart district: Alaska Territorial Department of Mines Miscellaneous Report 194-17, 8 p.
Smith, P.S., 1937, Mineral industry of Alaska in 1935: U.S. Geological Survey Bulletin 880-A, p. 1-95.
|Reporters||G.E. Graham (ADGGS)|
|Last report date||11/7/2000|