Nanjan

Prospect in Alaska, United States with commodity Molybdenum

Geologic information

Identification information

Deposit ID 10307662
Record type Site
Current site name Nanjan

Geographic coordinates

Geographic coordinates: -130.99474, 55.24075 (WGS84)
Relative position The Nanjan prospect is at an elevation of about 100 feet, about 0.2 mile from the shoreline of Behm Canal, and 0.4 mile east-southeast of Roe Point. The prospect is in the west wall of the gorge of a linear, unnamed creek that flows north-northwest into Behm Canal. The site is in section 33, T. 76 S., R. 96 E., of the Copper River Meridian. It corresponds to loc. 441 (1-3) in Maas and others (1995). The location is accurate within a few hundred feet.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Molybdenum Primary

Materials information

Materials Type of material
Molybdenite Ore
Pyrite Ore
Quartz Gangue

Mineral occurrence model information

Model code 85
USGS model code 22c
Deposit model name Polymetallic veins
Mark3 model number 46

Nearby scientific data

(1) -130.99474, 55.24075

Comments on the geologic information

  • Geologic Description = The Nanjan prospect area is underlain by an assemblage of undivided Mesozoic or Paleozoic metamorphosed sedimentary, volcanic, and intrusive rocks; and by a stock and dikes of Cretaceous granodiorite and quartz diorite (Berg and others, 1988, p. 21, 22). The undivided assemblage was regionally metamorphosed to amphibolite grade in middle or Late Cretaceous Cretaceous time, and locally remetamorphosed to hornblende hornfels near the contacts of some of the granodiorite and quartz diorite plutons. The prospect is situated on a prominent high-angle fault of unknown displacement that strikes north-northwest, along the valley of the unnamed creek that adjoins the property (Maas and others, 1995, fig. 70). The Nanjan prospect consists of sparse nodules of pyrite and molybdenite in a quartz fissure vein that reportedly lies near the contact of hornblende granite and altered limestone (Maas and others, 1995, p. 268). The vein strikes between N40W and N20E and dips generally to the west. the vein is up to 8 feet thick, but probably averages less than 3 feet thick; it is exposed intermittently along strike for at least 1300 feet. Most of the molybdenite is associated with fault gouge that bounds the vein. The vein apparently is younger than most or all of the middle or Late Cretaceous regional metamorphism, but older than an episode of local(?) faulting. Molybdenite mineralization was discovered at the Nanjan property in about 1935, Workings in the 1930s included trenches, opencuts, test pits, and shafts, but little of the work was evident in 1992 (Maas and others, 1995). Samples collected by Maas and others (1995, p. 269) along the Nanjan vein revealed low precious- and base-metal values. The highest molybdenum analysis was 0.25% Mo in a selected sample, and 0.20% Mo across a 4-foot-wide section of the vein.
  • Age = Late Cretaceous or younger

Economic information

Economic information about the deposit and operations

Development status Prospect

Mining district

District name Ketchikan

Comments on the workings information

  • Workings / Exploration = Molybdenite mineralization was discovered at the Nanjan property in about 1935, Workings in the 1930s included trenches, opencuts, test pits, and shafts, but little of the work was evident in 1992 (Maas and others, 1995). Samples collected by Maas and others (1995, p. 269) along the Nanjan vein revealed low precious- and base-metal values. The highest molybdenum analysis was 0.25% Mo in a selected sample, and 0.20% Mo across a 4-foot-wide section of the vein.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF KC105

Bibliographic references

  • 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 = Polymetallic vein? (Cox and Singer, 1986; model 22c)
Deposit Other Comments = the prospect is in Misty Fiords National Monument Wilderness.

Reporter information

Type Date Name Affiliation Comment
Reporter 04-JUL-99 H.C. Berg U.S. Geological Survey