Prospect in Alaska, United States with commodity Gold

Geologic information

Identification information

Deposit ID 10001578
MRDS ID A012331
Record type Site
Current site name Moonshine

Geographic coordinates

Geographic coordinates: -131.61677, 55.29085 (WGS84)
Relative position The Moonshine prospect is at sea level on southeastern Gravina Island, about 0.3 mile northwest of Gravina Point. The site is in section 8, T. 76 S., R. 91 E., of the Copper River Meridian. It corresponds to loc. 72 in Elliott and others (1978). The location is accurate within 0.1 mile.
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Geographic areas

Country State
United States Alaska


Commodity Importance
Gold Primary

Comments on the commodity information

  • Ore Material = Basemetal sulfides
  • Ore Material = Basemetal sulfides

Mineral occurrence model information

Model code 91
USGS model code 24b
Deposit model name Massive sulfide, Besshi (Japanese deposits)
Mark3 model number 30

Host and associated rocks

  • Host or associated Host
    Rock type Metamorphic Rock > Metavolcanic Rock > Mafic Metamorphic Rock > Greenstone
    Stratigraphic age (youngest) Late Cretaceous

Nearby scientific data

(1) -131.61677, 55.29085

Comments on the geologic information

  • Geologic Description = The country rocks on southeastern Gravina Island are Upper Jurassic or Cretaceous marine andesitic or basaltic volcanic rocks that are gradationally interbedded with subordinate flyschlike sedimentary rocks (Berg, 1973; Berg and others, 1988). The strata were regionally metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time. The country rocks are cut by intermediate or mafic dikes that apparently postdate the regional metamorphism.? Wright and Wright (1908, p. 179) describe the deposit as two parallel 'veins' that strike northwest, parallel to the foliation of altered greenschist hostrock. They do not describe the ore minerals, but the deposits probably contain basemetal sulfides and were prospected in the early 1900s chiefly for gold. The deposits are 6 and 18 feet thick and are separated by 50 feet of relatively barren rock. Although Wright and Wright do not mention quartz at the Moonshine, Elliott and others (1978) infer that the deposits are quartz veins. However, Wright and Wright's description, the geologic setting of the Moonshine prospect, and its proximity to other lode deposits on southeastern Gravina Island (KC073, 074), suggest instead that the Moonshine is mainly a stratiform deposit, comprising sulfide bands or disseminations parallel to the foliation of the schist hostrock. If so, the Moonshine may be a metamorphosed Besshi massive sulfide deposit of Late Jurassic age.
  • Age = Late Jurassic

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 in the early 1900s included a 30-foot-long opencut and a 12-foot shaft.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A012331
USGS Alaska Resource Data File ARDF KC075

Bibliographic references

  • Deposit

    Berg, H.C., 1973, Geology of Gravina Island Alaska: U.S. Geological Survey Bulletin 1373, 41 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

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

Comments on the references

  • Primary Reference = Wright and Wright, 1908; Berg, 1973

General comments

Subject category Comment text
Deposit Model Name = Besshi massive sulfide? (Cox and Singer, 1986; model 24b)

Reporter information

Type Date Name Affiliation Comment
Reporter 03-JUL-1999 H.C. Berg U.S. Geological Survey