|Quadrangle map, 1:250,000-scale||CR|
|Quadrangle map, 1:63,360-scale||C-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||In their text, Wright and Wright (1908) locate this prospect at an elevation of about 560 feet, about one-half mile west of the upper workings of the Gold Standard Mine (CR081). However, their small-scale, somewhat generalized map shows it about one-half mile northwest of the upper workings of the Gold Standard Mine; this would would place it at a considerable higher elevation of about 1,000 feet or more. For this record, the site follows their map and places the prospect about 0.5 mile east of the center of section 2, T. 72 S., R. 87 E. The location is probably accurate to within 0.5 mile.|
Geologic descriptionThe only working at the Midnight Sun prospect is a 15-foot open cut (Wright and Wright, 1908). A quartz vein 6 inches to 2 feet thick, that strikes N80W and dips 30N, cuts greenstone and greenschist. The vein and host rocks are cut by numerous faults that offset the vein. The vein includes fragments of wall rock, and minor pyrite and free gold. Apparently there has been no work on the prospect since 1908. The rocks in the area consist of metamorphosed andesite, basalt, agglomerate, and tuff, and minor flysch, shale, and phyllite. Eberlein and others (1983) and Brew (1996) consider them to be Paleozoic or Mesozoic in age; Gehrels and Berg (1992) tentatively mapped them as Jurassic or Cretaceous.
|Geologic map unit||(-132.020064094508, 55.6554075376021)|
|Mineral deposit model||Low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a).|
|Mineral deposit model number||36a|
|Age of mineralization||The quartz veins cut country rocks that may be as young as Cretaceous or as old as Paleozoic.|
|Workings or exploration||The only working is a 15-foot open cut.|
|Indication of production||None|
Brew, D.A., 1996, Geologic map of the Craig, Dixon Entrance, and parts of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2319, 53 p., 1 sheet, scale 1:250,000.
Clautice, K.H., Gilbert, W.G., Wiltse, M.A., and Werdon, M.B., 1994, Geology of the Helm Bay area, portions of the Craig C-1 and Ketchikan C-6 quadrangles, southeastern Alaska: Alaska Division of Geological and Geophysical Surveys Public-Data File 94-41, 1 sheet, scale 1:63,360.
Cobb, E. H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Craig quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-869, 262 p.
Eberlein, G.D., Churkin, Michael, Jr., Carter, Claire, Berg, H.C., and Ovenshine, A. T., 1983, Geology of the Craig quadrangle, Alaska: U.S. Geological Survey Open-File Report 83-91, 52 p.
Gehrels, G.E., and Berg, H.C., 1992, Geologic map of southeastern Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I-1867, 1 sheet, scale 1:600,000, 24 p.
|Reporters||D.J. Grybeck (Applied Geology)|
|Last report date||5/1/2004|