|Quadrangle map, 1:250,000-scale||SK|
|Quadrangle map, 1:63,360-scale||B-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This small mine is located at an elevation of between 1,820 and 1,850 feet on the west bank of McKinley Creek, about 2 miles above its junction with Porcupine Creek. it is shown as location 106 by Still and others (1984).|
The following is summarized from Bundtzen and Clautice (1986). In the vicinity of the Golden Eagle occurrence, the Porcupine Slate that host this prospect is a dark-gray, pyrite-rich, micaceous, carbonaceous slate to phyllite, with minor siltstone and metasandstone. Tan to brown, micaceous silica-carbonate bands are either beds or altered mafic dikes. The Golden Eagle lode is a quartz-pyrite-pyrrhotite-sphalerite fissure vein that cuts a 11- to 15-foot-wide, tan, silica-carbonate band. On the west side of McKinley Creek, the vein ranges from 3 inches to 27 inches thick, strikes N35-65W, and dips steeply northeast to vertical. The hanging wall of the vein contains a highly gossanous 3.5-foot-long by 0.5 to -1-foot wide wedge of bronze-colored pyrite, pyrrhotite, and minor sphalerite. Oxidation of the sulfides has left a vug of euhedral quartz crystals, ferricrete gossan, and local concentrations of very fine-grained free gold. Native sulfur spheres and masses up to 2 inches in diameter envelope clots of sulfide grains, particularly sphalerite. Vertically higher on the vein exposure, smaller pods of massive to disseminated pyrite, pyrrhotite, and minor sphalerite are localized along the hanging wall. The average sulfide content of the vein is only 5% to 8%. At least two phases of silica injection are apparent. The weighted average of six samples taken along 14 feet of exposed vein is 0.653 ounce of gold per ton, 0.227 ounces of silver per ton, and 0.45% zinc, with traces of copper, lead, and cobalt. Grab samples of five similar, smaller, quartz-sulfide veins downstream from the Golden Eagle lode averaged 0.495 ounce of gold per ton, and 0.043% zinc, with traces of cobalt, copper, and lead.
Still and others (1991) assert that the silica-carbonate bands are altered dikes of original mafic composition. Most of the quartz veins are transverse fracture fillings confined to the silica-carbonate-altered dikes.This small mine is within the northwest-trending zone of quartz-sulfide veining in sediments and slates in the Skagway B-4 quadrangle that is described by Wright (1904 [B 225 and B 236]), Eakin (1918 and 1919), and MacKevett and others (1974) and considered to be the source of placer gold in the area. These particular veins are probably one of the major gold sources for the McKinley Creek placer deposit (SK045) as little placer gold is found above this lode deposit.
|Geologic map unit||(-136.221858631145, 59.369667941866)|
|Mineral deposit model||Auriferous quartz-sulfide vein (Cox and Singer, 1986; model 22c).|
|Mineral deposit model number||22c|
|Age of mineralization||Unknown, but probably Cretaceous or younger based on the age of intrusives in area (MacKevett and others, 1974).|
|Alteration of deposit||The silica-carbonate units which are cut by or parallel the quartz-sulfide veins are probably altered mafic dikes (Still and others, 1991). Questionable mariposite, which may result from the alteration of mafic minerals, is also described (Bundtzen and Clautice, 1986).|
|Indication of production||None|
|Reserve estimates||Still and others (1991) concluded that, 'Except for the Vug vein, the 30 or so quartz ladder veins examined on this prospect are not large enough or close enough to be considered for mine development.' 'The Vug vein may indicate potential for isolated spots of high-grade gold mineralization...', '...values in the quartz veins do encourage further exploration for faults or other structures...', and 'The gold values in the slate suggest a possibility of low-grade large-volume gold mineralization.'|
|Production notes||Over 150 pounds of sulfides were reported mined from a large vug on the Vug vein from about 1983 to 1985 with the recovery of about 0.5 troy ounces of gold (Still and others, 1991).|
Bundtzen, T.K., and Clautice, K.H., 1986, Prospect examination of the Golden Eagle lode-gold prospect near Porcupine, Skagway B-4 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Public-Data File 86-18, 7 p.
Eakin, H.M., 1918, Gold placer mining in the Porcupine district: U.S. Geological Survey Bulletin 662-B, p. 93-100.
Eakin, H.M., 1919, The Porcupine gold placer district, Alaska: U.S. Geological Survey Bulletin 699, 29 p.
Gilbert and Redman, 1989;
Hoekzema, R.B., Fechner, S.A., and Bundtzen, T.K., 1986, Distribution, analysis, and recovery of placer gold from the Porcupine mining area, southeast Alaska: U.S. Bureau of Mines Open-File Report 89-86, 49 p., 4 sheets.
MacKevett, E.M., Jr., Robertson, E.C., and Winkler, G.R., 1974, Geology of the Skagway B-3 and B-4 quadrangles, southern Alaska: U.S. Geological Survey Professional Paper 832, 33 p., 1 plate.
Still, J.C., 1991, Section A: Haines - Klukwan - Porcupine subarea, in U.S. Bureau of Mines, Mineral investigations in the Juneau Mining District, Alaska, 1984-1988: Volume 2 - Detailed mine, prospect, and mineral occurrence descriptions: U.S. Bureau of Mines Special Publication VOL. 2A, 214 p., 9 sheets.
Still, J.C., Hoekzema, R.B., Bundtzen, T.K., Gilbert, W.G., Wier, K.R., Burns, L.E., and Fechner, S.A., 1991, Economic geology of Haines-Klukwan-Porcupine area, southeastern Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 91-4, 156 p., 5 sheets, scale 1:63,360.
Still, J.C., Weir, K.R., Gilbert, W.G., and Redman, Earl, 1984, Stream sediment, float, and bedrock sampling in the Porcupine mining area, southeast Alaska: U.S. Bureau of Mines Open-File Report 173-84, 6 p., 1 sheet, scale 1:250,000.
Wright, C.W., 1904, The Porcupine placer district, Alaska: U.S. Geological Survey Bulletin 236, 35 p.
|Reporters||T.C. Crafford (T. Crafford & Associates, Anchorage)|
|Last report date||2/4/2001|