|Quadrangle map, 1:250,000-scale||CR|
|Quadrangle map, 1:63,360-scale||A-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Wakefield prospect is at an elevation of about 1,300 feet, east of upper Lake Luelia. It is on the nose of the ridge that extends north-northwest from elevation 2577, and about 0.4 mile southeast of the center of section 29, T. 78 S., R. 88 E.|
As described by Wright and Wright (1906, 1908), the workings are a 50-foot shaft with mineralization exposed at the 25-foot level, and several open cuts. There was assessment work as late as 1915. The host rock is greenschist, slate and 'grits.' The deposit consists of a lenticular mass of chalcopyrite 10 feet thick in a 60-foot-thick mineralized layer in the schist that contains considerable pyrite, quartz, and epidote. The Wrights considered the deposit to be similar to the mineralization at the Niblack Mine (CR216). The prospect was examined by Maas and others (1992), who found a flooded shaft, a 17-foot adit, and some trenches. The workings expose a zone up to 100 feet wide of iron-stained, epidote-bearing, silicified greenschist that contains disseminations and layers of pyrite and chalcopyrite. Chip samples 1.3 to 4 feet long contained 221 to 656 parts per billion gold (ppb) and 851 to 7,566 parts per million (ppm) copper. A select sample contained 1,732 ppb gold, 47.2 ppm silver, and 6.57 percent copper.The age of the rocks in the area has been variously interpreted. Eberlein and others (1983) mapped the strata as locally metamorphosed graywacke of Silurian or Ordovician age, near a large Paleozoic or Mesozoic granitic intrusion. Gehrels (1992) and Maas and others (1995) mapped them as pre-Ordovician metamorphosed volcanic and sedimentary rocks near a Silurian or Ordovician granitic intrusion. Brew (1996) called them Late Proterozoic and Cambrian Wales Group schist, phyllite, and marble, near a Tertiary granitic intrusion of intermediate composition. Most recently, Slack and others (2002) and S.M. Karl (oral communication, 2003) mapped the strata as Silurian and Ordovician, low-grade, regionally metamorphosed sedimentary and volcanic rocks.
|Geologic map unit||(-132.179882632818, 55.0740107243298)|
|Mineral deposit model||Probably a Besshi-type, volcanogenic massive-sulfide copper deposit (Cox and Singer, 1986; model 24b).|
|Mineral deposit model number||24b|
|Age of mineralization||Probably contemporaneous with the deposition of the Silurian or Ordovician host rocks.|
|Alteration of deposit||Greenschist is iron stained and silicified.|
|Workings or exploration||Explored prior to WW I by a 50-foot shaft, a short adit, and several trenches.|
|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.
Chapin, Theodore, 1916, Mining developments in southeastern Alaska: U.S. Geological Survey Bulletin 642-B, p. 73-104.
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., 1992, Geologic map of southern Prince of Wales Island, southeastern Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I-2169, 23 p., 1 sheet, scale 1:63,360.
Maas, K.M., Bittenbender, P E., and Still, J.C., 1995, Mineral investigations in the Ketchikan mining district, southeastern Alaska: U.S. Bureau of Mines Open-File Report 11-95, 606 p.
Maas, K.M., Still, J.C., and Bittenbender, P.E., 1992, Mineral investigations in the Ketchikan mining district, Alaska, 1991 - Prince of Wales Island and Vicinity: U.S. Bureau of Mines Open-File Report 81-92, 69 p., 1 sheet, scale 1:20.
Slack, J.F., Shanks, W.C. III, Karl, S.M., Ridley, W.I., and Bittenbender, P.E., 2002, Geochemical and sulfur isotope compositions of Late Proterezoic and early Paleozoic volcanogenic massive sulfide deposits, Prince of Wales Island and vicinity, southeastern Alaska (abs.): Geological Society of America, Abstracts with Programs, v. 34 (6), p. 113.
Wright, F.E., and Wright, C.W., 1906, Lode mining in southeastern Alaska, in Brooks, A.H., 1906, Report on Progress of Investigations of Mineral Resources of Alaska in 1905: U.S. Geological Survey Bulletin 284, p. 30-54.
|Reporters||D.J. Grybeck (Applied Geology)|
|Last report date||5/1/2004|