Prospect in Alaska, United States with commodities Gold, Molybdenum, Copper

Geologic information

Identification information

Deposit ID 10308610
Record type Site
Current site name Venitia
Alternate or previous names Black Swan, Laundromat, Jim's cut

Geographic coordinates

Geographic coordinates: -131.62177, 55.32974 (WGS84)
Relative position This site represents four prospects or occurrences distributed along a northwest-trending line about a mile long on southwest Revillagigedo Island. They are at elevations ranging from near sea level to about 300 feet, and from about 0.4 to 1.5 miles southeast of Ketchikan Creek (sections 30 and 32, T. 75 S., R. 91 E., of the Copper River Meridian). The coordinates of the site are for the approximate midpoint of the line of prospects. The site includes loc. 66 in Elliott and others (1978), and locs. 281-283 in Maas and others (1995). The location is accurate within about 0.5 mile.
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Geographic areas

Country State
United States Alaska


Commodity Importance
Gold Primary
Molybdenum Primary
Copper Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Malachite Ore
Molybdenite Ore
Pyrite Ore


  • Local oxidation of copper minerals (Jim's cut).

Mineral occurrence model information

Model code 80
USGS model code 21b
Deposit model name Porphyry Mo, low-F

Nearby scientific data

(1) -131.62177, 55.32974

Comments on the geologic information

  • Geologic Description = This part of Revillagigedo Island is underlain mainly by marine, andesitic or basaltic volcanic rocks and interbedded pelitic sedimentary rocks that are intruded by Cretaceous stocks, sills, and dikes of feldspar-porphyritic granodiorite, and by a stock and probably related plugs of Tertiary gabbro (Berg and others, 1988). The strata were regionally metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time. They subsequently were contact metamorphosed to hornblende hornfels: locally, near some of the Cretaceous granodiorite contacts, and, more widely, peripheral to the Tertiary gabbro. The premetamorphic age range of the strata is uncertain. Berg and others (1988) note that they closely resemble Upper Jurassic to mid-Cretaceous flysch and volcanic rocks nearby on Gravina Island. The country rocks are cut by a high-angle fault along Tongass Narrows that displays about 4 miles of right-lateral offset. According to U.S. Bureau of Mines claim records (1977), the Venitia prospect, which appears to be in hornfelsed strata near the contact of a Tertiary gabbro stock, reportedly was staked for gold. No other information about this prospect has been made public. The following three occurrences were examined by Maas and others (1995, loc. 281-283), who named them either from U.S. Bureau of Mines claim records, or, informally, for local landmarks. Loc. 281 (Maas and others, p. 201): Black Swan. Samples of unidentified rock contained up to 555 ppm Cu. Loc. 282. Laundromat. A sample of unidentified rock contained 11 ppb Au. There is a 15-foot adit on this property. Loc. 283: Jim's cut. This occurrence, discovered during Maas and others' investigation, was exposed by residential and commercial development along the highway southeast of Ketchikan. It consists of diorite containing disseminated pyrite, chalcopyrite, molybdenite, and malachite that is exposed for 180 feet in a 12-foot deep cut in the back yards of several new houses. A 68-foot-long sample across disseminated sulfide mineralization in the diorite contained 163 ppb Au, 2632 ppm Cu, and 115 ppm Mo, Maas and others (1995, p. 201) interpret this occurrence as a porphyry molybdenum-type deposit.
  • Age = Probably Cretaceous (Jim's cut).

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 = Workings dating from the early 1900s have largely been covered by housing or commercial development, or plugged. At Jim's cut, a 68-foot-long sample across disseminated sulfide mineralization in the diorite contained 163 ppb Au, 2632 ppm Cu, and 115 ppm Mo (Maas and others, 1995, p. 201).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF KC069

Bibliographic references

  • Deposit

    U.S. Bureau of Mines, 1977, Claim map, Ketchikan quadrangle: U.S. Bureau of Mines Map 120, scale 1:250,000.

  • 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.

Comments on the references

  • Primary Reference = Maas and others, 1995

General comments

Subject category Comment text
Deposit Model Name = Porphyry Mo, low-F (Jim's cut) (Cox and Singer, 1986; model 21b)

Reporter information

Type Date Name Affiliation Comment
Reporter 02-JUL-1999 H.C. Berg U.S. Geological Survey