Portland

Prospect in Alaska, United States with commodities Copper, Lead, Zinc

Geologic information

Identification information

Deposit ID 10000193
MRDS ID A010230
Record type Site
Current site name Portland

Geographic coordinates

Geographic coordinates: -130.05481, 56.02171 (WGS84)
Relative position The Portland prospect is in Section 35 at an elevation of about 2200 feet on a northwest-facing mountainside overlooking the confluence of Salmon River and Texas Creek, and about 0.7 mile due east of the ruins at Ninemile (Elliott and Koch, 1981, p. 17, loc. 70).? Also see Additional Comments field, below.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Lead Primary
Zinc Primary

Materials information

Materials Type of material
Chalcopyrite Ore
Galena 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

Host and associated rocks

  • Host or associated Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite
  • Host or associated Host
    Rock type Metamorphic Rock > Metavolcanic Rock > Mafic Metamorphic Rock > Greenstone

Nearby scientific data

(1) -130.05481, 56.02171

Comments on the geologic information

  • Geologic Description = The country rocks in the area of the Portland prospect are the Triassic Texas Creek Granodiorite, which underlies and locally intrudes pelitic metasedimentary and subordinate andesitic (greenstone) metavolcanic strata of the Jurassic or older Mesozoic Hazelton Group; the Eocene Boundary Granodiorite, which intrudes the Hazelton and Texas Creek rocks; and still-younger Tertiary lamprophyre dikes, which cut all the other rocks (Smith, 1973, 1977; Koch, 1996).? Buddington's (1929, p. 84) description of the Portland group ambiguously includes information about the Hobo group, which he also describes separately (p. 84-85). (See Additional Comments field, below). The deposit is in greenstone and slate cut by a dike of granodiorite porphyry. On the Portland group, Buddington describes only a quartz vein along the slate-dike contact that contains many inclusions of the country rocks and which was exposed in an open cut. On the Hobo group, he describes a 2-3 foot quartz vein in the dike, and a 2-foot quartz vein in slate that was explored by a 15-foot adit and traced for 1500 feet by pits and surface exposures. The slate-hosted vein contains sparsely disseminated pyrite, galena, and sphalerite, and a little chalcopyrite. The slate also contains other quartz veins and stringers.

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Hyder

Comments on the workings information

  • Workings / Exploration = Quartz vein in slate was explored by pits and a 15-foot adit, probably in the 1920's.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A010230
USGS Alaska Resource Data File ARDF BC070

Bibliographic references

  • Deposit

    Buddington, A.F., 1929, Geology of Hyder and vicinity, southeastern Alaska, with a reconnaissance of Chickamin River: U.S. Geological Survey Bulletin 807, 124 p.

  • Deposit

    Smith, J.G., 1973, A Tertiary lamprophyre dike province in southeastern Alaska: Canadian Journal of Earth Sciences, v. 10, p. 408-420.

  • Deposit

    Smith, J.G., 1977, Geology of the Ketchikan D-1 and Bradfield Canal A-1 quadrangles, Alaska: U.S. Geological Survey Bulletin 1425, 49 p.

  • Deposit

    Elliott, R.L., and Koch, R.D., 1981, Mines, prospects, and selected metalliferous mineral occurrences in the Bradfield Canal quadrangle, Alaska: U.S. Geological Survey Open-File Report 81-728-B, 23 p., 1 sheet, scales 1:250,000 and 1:63,360.

  • Deposit

    Koch, R.D., 1996, Reconnaissance geologic map of the Bradfield Canal quadrangle, southeastern Alaska: U.S. Geological Survey Open-File Report 81-728-A, 35 p., 1 sheet, scale 1:250,000.

Comments on the references

  • Primary Reference = Buddington, 1929

General comments

Subject category Comment text
Deposit Model Name = Polymetallic veins
Deposit Other Comments = the Portland group was originally staked in 1919.? Buddington's (1929, p. 84) description of the Portland group ambiguously includes information about the adjoining Hobo group, which he also describes separately (p. 84-85). This record (BC070) summarizes Buddington's ambiguous description of the Portland(-Hobo) group, whereas BC071 summarizes Buddington's separate description of the Hobo group.

Reporter information

Type Date Name Affiliation Comment
Reporter 17-MAY-1998 H. C. Berg U.S. Geological Survey