|Quadrangle map, 1:250,000-scale||DN|
|Quadrangle map, 1:63,360-scale||C-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||
The Banjo mine (Cobb, 1980 [OFR 80-363]), on the unpatented Hardrock and Tugboat Annie claims, is on the ridge at the head of Lucky Gulch, a minor south-flowing tributary of Eureka Creek. The Banjo vein cropped out at an elevation of about 3200 feet. The main mine workings are about 0.28 mile south-southwest of the center of section 5, T. 16 S., R. 17 W., Fairbanks Meridian. The location is accurate within about 300 feet.The Banjo mine site is included in number 13 of Cobb (1972 [MF 366]), numbers 31 and 32 of Bundtzen, Smith and Tosdal (1976), location J of Hawley and Associates (1978), and occurrence 50 of Thornsberry, McKee, and Salisbury (1984). The mine is called the Red Top mine on the 1954 (revised 1978) edition of the Mt. McKinley C-2 quadrangle topographic map; it should be called the Banjo mine of the Red Top Mining Co.
The country rocks at the Banjo mine are graphitic schist, quartz-mica schist, and metafelsite of the lower Paleozoic Spruce Creek sequence (Bundtzen, 1981; Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrence 50).
The Banjo deposit is a 3- to 10-foot-thick quartz-carbonate-sulfide vein that on average strikes N 60 E and dips about 65 SE. It was developed for about 300 feet on the Banjo mine level, approximately at an elevation of 3140 feet, and was stoped from that level to the surface.
On the Banjo level, the vein is cut off to the east by a low-angle fault that strikes NNW and dips SW. The fault projects toward the Jupiter-Mars (DN102) adit, and could be the same fault that cuts off that vein. A mill level driven at an elevation of about 3010 feet appears to intersect the Banjo vein (called the Pas vein on that level), but it contains less gold and more base metals. The mill level apparently also intersects the NNW-striking fault that cuts off the productive vein on the Banjo level (Hawley and Associates, 1978; fig. 4.1-A(1)-4; Bundtzen, 1981, plate 3). The intermediate Quigley level apparently was not driven far enough to intersect either the Banjo vein or the fault (Wells, 1933, p. 370-371).
The productive part of the Banjo vein consists of quartz and carbonate that contains free gold, galena, arsenopyrite, pyrite, sphalerite, and tetrahedrite. The gold is in the quartz and in (or with) the sulfide minerals. Locally, the vein also contains scheelite, malachite, limonite, and scorodite.The gold-silver ratio in the vein appears to be about 1:1. The average grade of about 13,650 tons of ore was 0.52 ounce of silver per ton and 0.46 ounce of gold per ton. The concentrates contained 13.8 to 19.7 percent lead and about 0.9 to 1.6 percent zinc, and about 20 tons of lead-zinc concentrates were produced from the ore that was mined. The ore also averaged about 0.5 percent scheelite (Bundtzen, 1981).
|Geologic map unit||(, )|
|Mineral deposit model||Low-sulfide Au-quartz-(carbonate) vein, possibly grading with depth into a polymetallic vein (Cox and Singer, 1986; models 36a and 22c?).|
|Mineral deposit model number||36a, 22c?|
|Age of mineralization||The deposit is assumed to be Eocene (see record DN091).|
|Alteration of deposit||Local oxidation of iron, copper, and arsenic minerals.|
|Workings or exploration||
The deposit was discovered by tracing rich, gold-bearing quartz float on the east flank of Lucky Gulch. It was probably first developed by the so-called Upper Eureka tunnel (Capps, 1919, p. 101-102). Joe Quigley subsequently drove an adit below the area of float, but encountered only graphitic schist (Wells, 1933, p. 370-371). This level (Quigley) appears to lie between the Banjo level and lower mill level.The principal Banjo ore body was discovered sometime before 1938, and mined from 1939 through 1941. During that time it yielded more than 13,650 tons of ore that contained about 6,260 ounces of gold and 7,114 ounces of silver. A small amount of ore was probably mined in 1942.
|Indication of production||Yes|
|Reserve estimates||There is a small resource, established by drilling and underground workings during the mine operation. This resource is in caved underground workings and aggregates1595 tons of ore averaging 0.49 ounce of gold per ton (Bundtzen, 1981, pl. 3). Additional ore could occur between the Banjo and Mill levels west of the fault that cuts off the ore.|
|Production notes||The mine was the largest lode gold producer in the Kantishna district; it produced about 6,260 ounces of gold from 1939 through 1941.|
Additional commentsThe Banjo mine was the largest gold lode producer in the Kantishna Hills lode area (DN091). The claims at the mine, which is in Denali National Park and Preserve, were never patented.
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.
Bundtzen, T.K., Smith, T.E., and Tosdal, R.M., 1976, Progress report--Geology and mineral deposits of the Kantishna Hills: Alaska Division of Geological and Geophysical Surveys Open-File Report AOF-98, 80 p., 2 sheets, scale 1:63,360.
Cobb, E. H., 1972, Metallic mineral resources map of the Mount McKinley quadrangle, Alaska: U. S. Geological Survey Miscellaneous Field Studies Map MF-366, 1 sheet, scale 1:250,000.
Cobb, E.H., 1980, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mount McKinley quadrangle, Alaska: U. S. Geological Survey Open-File Report 80-363, 150 p.
Cox, D.P., and Singer, D.A., eds., 1986, Mineral deposit models: U.S. Geological Survey Bulletin 1693, 379 p.
Hawley, C. C. and Associates, Inc, 1978, Mineral appraisal of lands adjacent to Mt. McKinley National Park, Alaska: U. S. Bureau of Mines Open-File Report 24-78, 275 p. (paged by sections).
Thornsberry, V. V., McKee, C. J., and Salisbury, W. G., eds, 1984, 1983 Mineral Resource Studies: Kantishna Hills and Dunkle Mine Areas, Denali National Park and Preserve, Alaska: U. S. Bureau of Mines Open-File Report 129-84. 3 Volumes: v. 1, Text; v. 2, Appendices; v. 3, Maps. Prepared by Salisbury & Dietz, Inc., Spokane, WA.
|Last report date||4/22/2001|