|Quadrangle map, 1:250,000-scale||TN|
|Quadrangle map, 1:63,360-scale||A-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||
McCaskey Bar is a bench between Eureka and Kentucky Creeks. The site is at the mine symbol on the east side of Eureka Creek, in the southwest quarter of section 16, T. 4 N., R. 13 W., of the Fairbanks Meridian. According to Cobb (1972, location 42; 1977), the area of placer mining extends eastward from the mine symbol for about a mile. The western edge of the placer mine is apparently within a quarter mile of a landing strip to the northwest. The location is accurate within half a mile.This site is approximately 0.5 mile west of the site for McCaskey Bar, U.S. Bureau of Land Management MAS number 0020480048.
Bedrock in the area of the McCaskey Bar placer deposit consists of Jurassic or Cretaceous clastic sedimentary strata that are cut by thrust faults and locally intruded by one or more dikes of unknown composition (Chapman and others, 1982; Reifenstuhl and others, 1998). Mertie (1934) described the bedrock in the mined area as altered phyllite and argillite, often so decomposed that no hard rock could be found. A dike that cuts the country rock is just as altered, and quartz veins in the bedrock are also decomposed and iron-stained.
Mertie (1934) described McCaskey Bar as an old terrace placer east of Eureka Creek, approximately 250 feet above the active stream channel. The gold appears to be concentrated in the upper foot or so of the bedrock, but minor amounts also occur throughout the gravels in streaks at least 100 feet wide. Mertie reported the fineness of gold in one sample as 802.75. The largest nugget reported as of 1931 was worth $8.00 (gold at $20.67 per ounce). The heavy mineral concentrates contained ilmenite, picotite, cinnabar, and magnetite (Waters, 1934).Mining has been mainly by hydraulicking the frozen overburden and allowing the ground to thaw naturally. Water is scarce in summer and mining was intermittent (Mertie, 1934). Cobb's (1977) and Smith's (1933) reports of Farmer & Jones operating a hydraulic mine in 1928 in the Eureka Creek area actually refer to an operation on McCaskey Bar (Wimmler, 1926). Ray C. Pittman operated a bulldozer just south of McCaskey Bar on Eureka Creek in 1975 (Carnes, 1976).
|Geologic map unit||(-150.215561490869, 65.1670523837628)|
|Mineral deposit model||Placer Au (Cox and Singer, 1986; model 39a).|
|Mineral deposit model number||39a|
|Age of mineralization||Quaternary.|
|Workings or exploration||McCaskey Bar was mined by hydraulic methods and sluicing starting in 1924 and continued through the 1930s (Mertie, 1934). Cobb's (1977) and Smith's (1933) reports of Farmer & Jones operating a hydraulic mine in 1928 in the Eureka Creek area actually refer to an operation on McCaskey Bar (Wimmler, 1926, 1930). Ray C. Pittman operated a bulldozer just south of McCaskey Bar on Eureka Creek in 1975 (Carnes, 1976).|
|Indication of production||Yes; small|
|Production notes||No official records of production from McCaskey Bar have been made public.|
Bottge, R.G., 1986, Maps summarizing land availability for mineral exploration and development in northcentral Alaska, 1985: U.S. Bureau of Mines Open-File Report 70-86, 14 sheets.
Carnes, D.R., 1976, Active Alaskan placer operations, 1975: U.S. Bureau of Mines Open-File Report 98-76, 90 p., 40 plates, scale 1:250,000.
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.
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.
Reifenstuhl, R.R., Dover, J.H., Newberry, R.J., Clautice, K.H., Pinney, D.S., Liss, S.A., Blodgett, R.B., and Weber, F.R., 1998, Geologic map of the Tanana A-1 and A-2 quadrangles, central Alaska: Alaska Division of Geological & Geophysical Surveys Public Data File 98-37A v. 1.1, 19 p., 1 sheet, scale 1:63,360.
Smith, P.S., 1933, Mineral industry of Alaska in 1931: U.S. Geological Survey Bulletin 844-A, p. 1-81.
Waters, A.E., 1934, Placer concentrates of the Rampart and Hot Springs district: U.S. Geological Survey Bulletin 844-D, p. 163-246.
|Reporters||G.E. Graham (ADGGS)|
|Last report date||12/10/2000|