U.S.

Prospect in Alaska, United States with commodity Gold

Geologic information

Identification information

Deposit ID 10001564
MRDS ID A012312
Record type Site
Current site name U.S.

Geographic coordinates

Geographic coordinates: -131.97068, 55.59863 (WGS84)
Relative position The U.S. prospect is at an elevation of about 250 feet, 0.4 mile northeast of the head of the falls at the mouth of Falls Creek. The site is in section 30, T. 72 S., R. 88 E., of the Copper River Meridian. It corresponds to loc. 258 in Maas and others (1995, fig. 46), and to loc. 37 in Elliott and others (1978). The location is accurate within 0.1 mile.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary

Materials information

Materials Type of material
Gold Ore
Pyrite Ore
Quartz Gangue

Alteration

  • (Local) Pyritization of chlorite schist.

Mineral occurrence model information

Model code 75
USGS model code 19c
BC deposit profile E03
Deposit model name Distal disseminated Ag-Au
Mark3 model number 18

Host and associated rocks

  • Host or associated Host
    Rock type Metamorphic Rock > Schist

Nearby scientific data

(1) -131.97068, 55.59863

Comments on the geologic information

  • Geologic Description = The country rocks near this site include gray and green phyllite and semischist derived from intertonguing flysch and andesitic and basaltic volcanic rocks (Berg and others, 1988, p. 17-20); and gray felsic schist possibly derived from silicic tuff (Maas and others, 1995, p. 183 and fig. 46). Near Smugglers Cove, the bedded rocks are intruded by diorite that may be transitional to the andesitic and basaltic volcanic rocks. The bedded and intrusive rocks were regionally metamorphosed to greenschist grade in Late Cretaceous time (Brew, 1996, p. 27). Their premetamorphic age is uncertain. Berg and others (1988, p. 17) note that the intertonguing flysch and volcanic rocks closely resemble Upper Jurassic to mid-Cretaceous marine strata nearby on Gravina Island.? the deposit consists either of (1) auriferous, pyrite-bearing quartz that forms irregular lenses parallel to the foliation of pyritic chlorite schist (Wright and Wright, 1908, p. 157); or (2) an auriferous pyritic quartz vein 10-20 feet wide that strikes NW and dips 70 NE (Brooks, 1902, p. 57). The deposit was explored in the early 1900s by stripping and by a 6-foot-long adit.? Maas and others (1995, p. 184 and tables 25 and 26) suggest that the U.S. deposit may be part of a belt of exhalative volcanogenic gold deposits (KC035) that extends along the northeast shore of Smugglers Cove and includes the Mary T. (KC036) and Blue Bucket (KC039) deposits. The average metal contents of their samples of the U.S. deposit are: 1.45 ppm Au, 0.15 ppm Ag, 45 ppm Cu, 67.8 ppm Pb, and 124 ppm Zn.

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Mining district

District name Ketchikan

Comments on the workings information

  • Workings / Exploration = The deposit was explored in the early 1900s by stripping and by a 6-foot-long adit. The average metal contents of samples of the U.S. deposit collected in the early 1990s by the U.S. Bureau of Mines are 1.45 ppm Au, 0.15 ppm Ag, 45 ppm Cu, 67.8 ppm Pb, and 124 ppm Zn (Maas and others, 1995, table 25).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A012312
USGS Alaska Resource Data File ARDF KC037

Bibliographic references

  • Deposit

    Brooks, A.H., 1902, Preliminary report on the Ketchikan mining district, Alaska, with an introductory sketch of the geology of southeastern Alaska: U.S. Geological Survey Professional Paper 1, 120 p.

  • Deposit

    Wright, F.E., and Wright, C.W., 1908, The Ketchikan and Wrangell mining districts, Alaska: U.S. Geological Survey Bulletin 347, 210 p.

  • Deposit

    Elliott, R.L., Berg, H.C., and Karl, Susan, 1978, map and table describing metalliferous and selected nonmetalliferous mineral deposits, Ketchikan and Prince Rupert quadrangles, Alaska: U.S. Geological Survey Open-file Report, 78-73-B,17 p., scale 1:250,000.

  • Deposit

    Berg, H.C., Elliott, R.L., and Koch, R.D., 1988, Geologic map of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Mineral Investigations Series Map MF-1807,27 p., scale 1:250,000.

  • Deposit

    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.

  • Deposit

    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.

Comments on the references

  • Primary Reference = Brooks, 1902; Maas and others, 1995

General comments

Subject category Comment text
Deposit Model Name = Distal disseminated Ag-Au? (Bliss, 1992, model 19c)

Reporter information

Type Date Name Affiliation Comment
Reporter 30-JUN-1999 H.C. Berg U.S. Geological Survey