|Quadrangle map, 1:250,000-scale||LC|
|Quadrangle map, 1:63,360-scale||C-5|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||Locality is a 215 m long cut along Synneva Creek, about 270 m upstream from confluence of Bonanza Creek and Synneva Creek. This is part of locality 7 Nelson and others (1985) and locality 7 of Cobb (1972). SE1/4SW1/4 sec. 10, T. 7 N., R. 31 W., of the Seward Meridian. Locality is accurate to within 100 m.|
Geologic descriptionSynneva (Scynneva) Creek is a placer gold deposit. Analysis of heavy concentrates yield 60 percent cassiterite and 1.36 percent tungsten (Eakins and others, 1978). Jasper (1961) reported: evidence indicates that glacial scouring was not an important erosional factor in this area, it is believed that pre-glacial alluvials were undisturbed, and that placer gold concentrations remain more or less as originally deposited along the creek. The valley alluvials are mostly uniform gravels with some boulders, interpreted as reworked glacial deposits. Bedrock is shale, argillite, and graywacke cut by porphyritic granitic dikes. The sediments strike N 40 to 45 E, and dip varies from 60 to 75 SW.
|Geologic map unit||(-154.705257414242, 60.7073229073945)|
|Mineral deposit model||Placer Au (Cox and Singer, 1986; model 39a)|
|Mineral deposit model number||39a|
|Age of mineralization||Quaternary.|
|Alteration of deposit||Not applicable|
|Workings or exploration||
Work began in about 1957, and was limited to hand methods (ground-sluice and shovel-in). One man worked the mouth of the narrow gulch moving about 800 to 900 cubic yards, from which an unconfirmed $1,200 was recovered. There was no evidence to indicate that bedrock had been reached (Jasper, 1961).Analysis of heavy concentrates yield 60 percent cassiterite and 1.36 percent tungsten (Eakins and others, 1978).
|Indication of production||Yes; small|
|Reserve estimates||No reserves|
|Production notes||Jasper (1961) mentioned about 35 oz Au production, but probably much more was unreported (Eakins and others, 1978).|
Additional commentsEssentially part of the Bonanza Creek placer deposit.
Cobb, E.H., 1972, Metallic mineral resources map of the Lake Clark quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-378, 1 sheet, scale 1:250,000.
Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Iliamna, Lake Clark, Lime Hills, and McGrath quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-485, 101 p.
Cobb, E.H., and Reed, B.L., 1981, Summaries of data on and lists of references to metallic and selected nonmetallic mineral occurrences in the Iliamna, Lake Clark, Lime Hills, and McGrath quadrangles, Alaska; Supplement to Open-File Report 76-485; Part A, Summaries to January 1, 1981: U.S. Geological Survey Open-File Report 81-1343-A, 25 p.
Cobb, E.H., and Reed, B.L., 1981, Summaries of data on and lists of references to metallic and selected nonmetallic mineral occurrences in the Iliamna, Lake Clark, Lime Hills, and McGrath quadrangles, Alaska; Supplement to Open-File Report 76-485; Part B, Lists of references to Januray 1, 1981: U.S. Geological Survey Open-File Report 81-1343-B, 20 p.
Eakins, G.R., Gilbert W.G., and Buntzen, T.K., 1978, Preliminary bedrock geology and mineral resource potential of west-central Lake Clark quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Open-File Report 118, 15 p., 2 plates, scale 1:25,000.
Jasper, M.W., 1961, Bonanza Creek placers, Lake Clark quadrangle, in Williams, J.A., Report of the Division of Mines and Minerals for the year 1961: Alaska Division of Mines and Minerals Annual Report, p. 58-64.
|Reporters||M.L. Miller (USGS); D.P. Bickerstaff (USGS)|
|Last report date||6/15/1998|