Kantishna Hills placer deposts

Mines, Inactive

Commodities and mineralogy

Main commodities Au
Other commodities Ag; Mn; Pb; Sb; Sn; W
Ore minerals cassiterite; galena; gold; pyrite; rhodonite; scheelite; stibnite; wolframite
Gangue minerals garnet; ilmenite; magnetite; quartz

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale C-2
Latitude 63.5581
Longitude -150.8586
Nearby scientific data Find additional scientific data near this location
Location and accuracy This record summarizes information about the most significant placer gold deposits in the Kantishna Hills area. As defined here, the area is bounded on the east by the midline of R.16 W., Fairbanks Meridian, and on the west by Moose Creek. It approximately coincides with the main placer area of Thornsberry, McKee, and Salisbury (1984, fig. K-3), and includes the most important creeks, as well as many of the secondary ones. For this record, the location is approximately at the center of the area. It is at an elevation of 3835 feet near the crest of a hill, in the NW1/4 of section 4, T. 16 S., R. 17 W., Fairbanks Meridian. Most of the deposits included in this summary are briefly described by Cobb (1972 [MF 366], 1973 [B 374], 1980, [OFR 80-363]) and by Thornsberry, McKee, and Salisbury (1984).

Geologic setting

Geologic description

The most important placer creeks in the Kantishna district drain an area underlain chiefly by rocks of the Spruce Creek sequence (see MM091) (Bundtzen, 1981). Creeks that mostly drain Birch Creek Schist are, in general, smaller producers (Levell, 1984, fig. K-7 [v. 1]).
Placer deposits in the main part of the Kantishna Hills range from small colluvial-alluvial deposits at the heads of the valleys to medium-size alluvial deposits in relatively narrow tributary valleys. In turn, the narrow valley deposits grade into broad alluvial plain placers at the edge of the hills (Cobb, 1973 [B 1474]; Bundtzen, 1981; Levell, 1984 [v. 1]). At the upstream end, the colluvial and alluvial deposits rest on and grade into lode deposits.
Gravels are thin to almost absent in the alluvial deposits; these deposits mainly consist of angular unsorted bedrock material; gold is angular, locally crystalline and in composite nuggets of gold and quartz. Alluvium in the broad alluvial plain deposits, including lower Caribou Creek (MM035), is mostly composed of rounded to subrounded gravel stained and weakly cemented by groundwater precipitates. Gold tends to be fine and moderately well worn. With the exception of a deposit at the junction of the East and West Forks of Glen Creek, where gravel is at least 35 feet thick, most productive gravels are 15 or less feet thick.
There are two main types of placer deposits. One consists of alluvium in relatively narrow tributary valleys and in broad, low-gradient streams. The other consists of lowland alluvium and fluvio-glacial deposits (Levell, 1984 [v. 1]). The deposit in Eureka Creek (MM122) typifies the tributary valley type. The Caribou Creek deposit (MM035) exemplifies a lowland alluvial deposit, and most of the deposits on Moose Creek (MM132) are of fluvio-glacial origin. Most of the remaining placer resources in the Kantishna Hills area are in the low-gradient streams (Hawley and Associates, 1978; Levell, 1984).
The accessory mineral suite varies widely. In the tributary valley deposits, especially at their upper ends, the placers contain abundant mechanically unstable minerals such as pyrite, galena, and stibnite. Magnetite and garnet are probably the most common accessory minerals, and scheelite is widely distributed. Cassiterite occurs in several creeks. Wolframite was tentatively identified in one placer. Galena occurs in masses several inches across in Friday, Eureka, and other creeks, and boulders of rhodonite occur in Glen Creek. Ernie Mauer reported scheelite boulders as much as a foot across in upper Caribou Creek (Bundtzen, 1981, p. 165).
Placer gold in the Kantishna Hills area has the lowest mean purity (789 fine) of any district in Alaska; it also the largest coefficient of variation and the lowest reported value of 567 on nearby Little Moose Creek (Bundtzen, 1981, p. 163-164). Gold from creeks draining auriferous lode deposits, such as Eureka Creek, is as much as 900 fine. Caribou Creek (MM109), the most productive placer in the area, drains an area of lode deposits near Spruce and Kankone Peaks. The average gold fineness in the upper part of the creek was about 675; on lower Caribou, it ranged from about 680 to 700.
Geologic map unit (-150.860885906905, 63.5575958080121)
Mineral deposit model Au-PGE placer (Cox and Singer, 1986; model 39a). The deposits range from residual (eluvial) to colluvial in upper tributary valleys to alluvial and fluvio-glacial valley bottom deposits.
Mineral deposit model number 39a
Age of mineralization The placer deposits are as old as late Tertiary. The most important deposits are Pleistocene and Holocene.

Production and reserves

Workings or exploration Placer gold was discovered in the Kantishna Hills in 1905 and a rush ensued (Prindle, 1907, 1911; Capps, 1919; Bundtzen, 1978). The richest deposits were probably mined by the end of 1907. Medium- to large-scale hydraulic placer mining was attempted in 1922 to 24 but was generally unsuccessful (Davis, 1923). Medium-scale mining with 'dry land dredges' or mobile washing plants commenced in 1939; those operations were successful and continued through 1942. Mining began again in 1946 and continued for a few years, but was less successful than the pre-war years because of the fixed price of gold and higher costs. Small-scale mining continued with sniping of remaining rich deposits, and medium-scale mining resumed in about 1973-75, after the price of gold was allowed to float on the world market. Many of the small, rich deposits were also mined at that time. This mining terminated in about 1985, when an injunction halted mining pending judicial review.
Indication of production Yes; medium
Reserve estimates Significant gold resources remain in Caribou Creek and its benches; probably in Glacier Creek; and possibly in Moose Creek. The rich upland creeks, including Eureka, Friday, and Glen, have been extensively mined and contain relatively small resources. Flat Creek contains a significant amount of alluvium and is essentially unevaluated (Levell, 1984 [v. 2]). Unlike Caribou and Glacier Creeks, Flat Creek does not drain a significant area of Spruce Creek sequence rocks (see MM091).
Production notes The following creeks in the Kantishna district are ranked in descending order of production of placer gold: Upper Caribou (MM042), more than 20,000 ounces; Eureka (MM122), more than 10,000 ounces; and five creeks that produced at least 5000 ounces each, including Moose (MM132), Friday (MM113), Glacier (MM048), Lower Caribou (MM035), and Glen (MM108). Eldorado (MM028), Spruce (MM104), and Yellow (MM079) creeks each produced at least 1000 ounces of gold, and Last Chance (MM050), Crevice (MM046), and Rainy (MM130) creeks each produced at least 500 ounces of gold. Crooked Creek (MM013) and Little Moose (MM140) Creek, which are outside the Kantishna Hills placer area as herein defined, produced 1000 or more ounces of gold. The cumulative production of placer gold in the Kantishna district is more than 62,000 fine ounces.

Additional comments

There appear to be significant placer gold resources in the Kantishna district (Levell, 1984).

References

MRDS Number A010749

References

Bundtzen, T.K., 1978, A history of mining in the Kantishna Hills: The Alaska Journal, v. 8, no 2., p. 150-161.
Bundtzen, T.K., 1981, Geology and mineral deposits of the Kantishna Hills, Mt. McKinley quadrangle, Alaska: M. S. Thesis, University of Alaska, College, Alaska, 238 p.
Reporters C.C. Hawley
Last report date 4/20/2001