|Quadrangle map, 1:250,000-scale||SR|
|Quadrangle map, 1:63,360-scale||D-3|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The prospect is southwest of the head of Derickson Bay at an elevation of about 600 feet. It is in the N1/2 section 15, T. 9 N., R. 9 E., of the Seward Meridian. This is location 184 of Tysdal (1978 [MF-880-A]) and location S-123 of Jansons and others (1984). This location is accurate to within half a mile.|
The Eldorado prospect consists of a 12- to 48-inch-wide quartz vein in a shear zone. The vein is semi-concordant to the shear. It strikes N40E, dips 75NW, and is traceable for 400 feet along strike (Johnson, 1914 [B 592-G, p. 235]). The country rock is slate and quartzite of the Valdez Group of Late Cretaceous age (Cobb and Tysdal, 1980). The shear zone hosting the vein is related to the Contact Fault, a major regional structure that separates the Valdez Group from the younger Orca Group.Overall, the vein is composed of bluish-gray quartz that contains calcite, arsenopyrite, chalcopyrite, pyrite, pyrrhotite, and gold. Grab samples assayed as much as $5 in gold (gold at 20.67 per ounce) (Johnson, 1914 [B 592-G, p. 235]). Johnson (1914 ) reported that 375 feet of workings had been completed in 1913. No other information about this prospect has been made public. In 1978 and 1979, the U.S. Bureau of Mines searched for this prospect, but no workings were found (Hoekzema and Sherman, 1983).
|Geologic map unit||(-147.834072188872, 60.8714714263601)|
|Mineral deposit model||Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)|
|Mineral deposit model number||36a|
|Age of mineralization||Oligocene or younger; the Contact Fault cuts Oligocene intrusive rocks northeast of this prospect.|
|Workings or exploration||Johnson (1914 [B 592-G, p. 235]) reported that 375 feet of workings had been completed in 1913. Johnson also reported that samples of blue-gray quartz from the shear zone were reported to contain $100 in gold per ton (gold at $20.67/ounce), and samples of the sheared material contained $4.00 to $5.00 in gold per ton.|
|Indication of production||None|
Cobb, E.H., and Richter, D.H., 1972, Metallic mineral resources map of the Seward quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-466, 2 sheets, scale 1:250,000.
Cobb, E.H., and Tysdal, R.G., 1980, Summaries of data on and list of references to metallic and selected nonmetallic mineral deposits in the Blying Sound and Seward quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-621, 276 p.
Condon, W.H., and Cass, J.T., 1958, Map of a part of the Prince William Sound area, Alaska, showing linear geologic features as shown on aerial photographs: U.S. Geological Survey Miscellaneous Investigations Series Map I-273, 1 sheet, scale 1:125,000.
Jansons, Uldis, Hoekzema, R.B., Kurtak, J.M., and Fechner, S.A., 1984, Mineral occurrences in the Chugach National Forest, southcentral Alaska: U.S. Bureau of Mines Mineral Land Assessment 5-84, 218 p., 2 sheets, scale 1:250,000.
Johnson, B.L., 1914, The Port Wells gold-lode district, Alaska: U.S. Geological Survey Bulletin 592-G, p. 195-236.
Johnson, B.L., 1915, Mining on Prince William Sound: U.S. Geological Survey Bulletin 622-E, p. 131-139.
MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.
|Reporters||Jeff A. Huber ( Anchorage)|
|Last report date||1/1/2000|