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Alamo

Prospect in Alaska, United States with commodities Silver, Copper, Zinc
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Commodities
  6. Materials information
  7. Alteration
  8. Mineral occurrence model information
  9. Host and associated rocks
  10. Nearby scientific data
  11. Economic information about the deposit and operations
  12. Mining district
  13. Links to other databases
  14. Bibliographic references
  15. General comments
  16. Reporter information

Geologic information

Identification information

Deposit ID 10001552
MRDS ID A012299
Record type Site
Current site name Alamo
Alternate or previous names Glacier
Related records 10160940

Geographic coordinates

Geographic coordinates: -130.75787, 55.75587 (WGS84)
Relative position The Alamo (Glacier) prospect is at an elevation of about 200-1000 feet above the north shore of Walker Cove, about 6.3 miles northeast of Hut Point. The prospect is along the northeast wall of a steep, southeast-trending gorge, in section 31, T. 70 S., R. 96 E., of the Copper River Meridian. It corresponds to loc. P-18 in Berg and others (1977, p. 116-120), and to loc. 22 in Elliott and others (1978). The location is accurate within 0.2 mile.

Site location context

Political divisions (FIPS codes)

Prince of Wales-Hyder(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Ketchikan D-3(quadrangle 1:63,360 scale)

Ketchikan NW(quadrangle 1:100,000 scale)

Ketchikan(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Southern Southeast Alaska(hydrologic accounting unit)

Southeast Alaska(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Misty Fiords National Monument Wilderness(Wilderness)

Wilderness FS(Type of land area)

FS(Federal land areas administered by FS)

Tongass National Forest(National Forest)

National Forest FS(Type of land area)

FS(Federal land areas administered by FS)

Misty Fjords National Monument Wilderness(Wilderness)

Wilderness FS(Type of land area)

FS(Federal land areas administered by FS)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Copper Primary
Zinc Critical Primary

Materials information

Materials Type of material
Chalcopyrite Ore
Pyrite Ore
Pyrrhotite Ore
Sphalerite Ore
Quartz Gangue

Alteration

  • (Local) Locally conspicuous iron-staining.

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 Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite
    Stratigraphic age (youngest) Pliocene
  • Host or associated Host
    Rock type Metamorphic Rock > Gneiss

Nearby scientific data

(1) -130.75787, 55.75587
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The area of the Alamo prospect is underlain by a sequence of pelitic and quartzofeldspathic paragneiss, and minor dolomite marble that is part of a large metamorphic roof pendant in Tertiary or Cretaceous foliated granodiorite and quartz diorite of the Coast Range batholith (Berg and others, 1977, p. 117; Berg and others, 1988). The metamorphic sequence represents marine strata that underwent high-grade regional metamorphism in Cretaceous or Tertiary time. The premetamorphic age of the strata is uncertain, but they probably are mainly Paleozoic and may be as old as Precambrian (Berg and others, 1988, p. 26; Gehrels and others, 1990; Crawford and others, in press).? the deposit is a 75-foot-wide sulfide-bearing zone in paragneiss near the contact of foliated granodiorite (Berg and others, 1977, p. 117-120). The zone strikes northwest and dips northeast, parallel to the regional foliation of the country rocks. At an elevation of about 870 feet, the paragneiss contains a layer of dolomite marble about 18 feet thick. From 0-18 feet above the marble, the paragneiss contains small amounts of pyrite and subordinate chalcopyrite. The next nine feet contain sparse pyrite and a trace of chalcopyrite. The marble appears to be barren. Other parts of the deposit contain seams, patches, and disseminated grains of chalcopyrite and pyrrhotite. The richest material sampled by the U.S. Bureau of Mines in 1972 was a small lens of massive chalcopyrite and other sulfides, accompanied by some quartz and breccia, about 15 inches thick and 30 inches long (Berg and others, 1977, p. 120 and table 11, no. 2P025). Atomic absorption assays of this material showed 10% Cu, 0.2% Zn, 50 ppm Ag, and 0.2 ppm Au. The zinc content in this sample, and the zinc content in several samples collected elsewhere in the deposit, indicate that sphalerite also is present. Twenty-six channel samples at several places along the deposit were collected by the Bureau in 1972 (Berg and others, 1977, p. 117-120). Assays of these samples showed up to 10% Cu and 2.1% Zn, along with as much as 75 ppm Pb, 50 ppm Ag, 15 ppm Mo, and, in one sample, 0.2 ppm Au. The results of this sampling indicate a large body of sulfide-bearing paragneiss containing 0.2%-0.7% Cu.

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 located as the Glacier prospect in 1954 and explored by a small amount of trenching and some core drilling (Berg and others, 1977, p. 116-117). It was restaked in 1969 by another locator as the Alamo group of six claims. Exploration since the restaking included some stripping, several shallow trenches, and 5 diamond drill holes. Four of the holes reportedly were 180 feet long and one was 90 feet long. Two additional claims were located in 1973, but at that time no assay values or logs had yet been released for any of the drill holes. Although results of this private exploration have not been made public, sample values were unofficially reported to range from 0.25%-1.3% Cu in the limited areas sampled. Other unofficial reports described several drill-hole intersections of 18- to 27-foot-long zones containing more than 1% Cu (Berg and others, 1977, p. 120). Continuity of these intersections between holes is uncertain.? Twenty-six channel samples at several places along the deposit were collected by the U.S. Bureau of Mines in 1972 (Berg and others, 1977, p. 117-120). Assays of these samples showed up to 10% Cu and 2.1% Zn, along with as much as 75 ppm Pb, 50 ppm Ag, 15 ppm Mo, and, in one sample, 0.2 ppm Au. The results of this sampling indicate a large body of sulfide-bearing paragneiss containing 0.2%-0.7% Cu.

Reference information

Comments on the references

  • Primary Reference = Berg and others, 1977

General comments

Subject category Comment text
Deposit Model Name = Metamorphosed Besshi massive sulfide? (Cox and Singer, 1986; model 24b)
Deposit Other Comments = Prospect is in Misty Fiords National Monument Wilderness.

Reporter information

Type Date Name Affiliation Comment
Reporter 29-JUN-1999 H.C. Berg U.S. Geological Survey

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Maps centered on this site

Authoritative Alaska resources

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