|Quadrangle map, 1:250,000-scale||SD|
|Quadrangle map, 1:63,360-scale||C-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Sulphide prospect is near the cabin shown on the USGS 1:63,360-scale topographic map, about 3.2 miles west of the center of the mouth of Fords Terror. It is near the northwest corner of section 20, T. 49 S., R. 76 E.|
Geologic descriptionThe Sulphide prospect was originally staked in 1928 and subsequently restaked in 1939, 1955, 1969 and 1970, and 1975 (Roehm, 1942 [IR 195-33]; Kimble and others, 1984). The deposit consists of a zone 5 to 15 feet wide with disseminated and banded massive-sulfide minerals. The zone can be traced for at least 830 feet in five trenches. The host rock is iron-stained feldspathic gneiss and quartzite, part of the Cretaceous biotite-schist unit of Brew and Grybeck (1984). The sulfides include sphalerite, galena, chalcopyrite, pyrrhotite, and marcasite. The sulfides are both disseminated and in bands up to 0.4 foot thick parallel to the foliation of the metamorphic host rocks. Locally the sulfides are remobilized and concentrated in the noses of small folds. Kimble and others (1984) collected 21 channel samples across the zone in 4 trenches. The five with the highest metal values varied from 4.4 to 7.0 feet in length and contained 0.02-0.25 percent copper, 0.65-1.30 percent lead, 1.25-1.90 percent zinc, 0.02-0.88 ounce of silver per ton, and nil to 0.004 ounce of gold per ton.
|Geologic map unit||(-133.269894886404, 57.6140517711739)|
|Mineral deposit model||Metamorphosed, volcanogenic massive-sulfide deposit?|
|Age of mineralization||In gneiss and quartzite of Cretaceous (metamorphic) age; the age of the protolith is unknown.|
|Workings or exploration||The deposit has been explored by 5 short trenches.|
|Indication of production||None|
Additional commentsThe prospect is in the Tracy Arm-Fords Terror Wilderness Area which is closed to mineral exploration and mining.
Brew, D.A., and Grybeck, Donald, 1984, Geology of the Tracy Arm-Fords Terror wilderness study area and vicinity, Alaska, in U.S. Geological Survey and U.S. Bureau of Mines, Mineral resources of the Tracy Arm-Fords Terror wilderness study area and vicinity, Alaska: U.S. Geological Survey Bulletin, 1525, p. 19-52.
Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Sumdum and Taku River quadrangles, Alaska: U.S. Geological Survey Open-File Report 78-698, 64 p.
Kimble, A.L., Still, J.C., and Rataj, J.L., 1984, Mineral deposits and occurrences in the Tracy Arm-Fords Terror wilderness study area and vicinity, Alaska, in U.S. Geological Survey and U.S. Bureau of Mines, Mineral resources of the Tracy Arm-Fords Terror wilderness study area and vicinity, Alaska: U.S. Geological Survey Bulletin 1525, p. 105-210.
Roehm, J.C., 1942, Summary report of mining investigations and itinerary of J. C. Roehm in the Ketchikan, Wrangell, Petersburg and Juneau mining precincts: Alaska Territorial Department of Mines Itinerary Report 195-33, 23 p.
|Reporters||Donald Grybeck (U.S. Geological Survey)|
|Last report date||10/8/2004|