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Snowstorm

Prospect in Alaska, United States with commodity Gold
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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 10001558
MRDS ID A012306
Record type Site
Current site name Snowstorm
Alternate or previous names Last Chance (Helm Bay), Beulah

Geographic coordinates

Geographic coordinates: -131.99568, 55.64474 (WGS84)
Relative position This site, in section 12, T. 72 S., R. 87 E., of the Copper River Meridian, represents three prospects on the southwest side of Helm Bay, about 5 miles from the mouth of the bay. The Snowstorm and Last Chance (Helm Bay) prospects are at or near sea level, and the Beulah prospect is at an elevation of about 150 feet (Maas and others, 1995, fig. 46). The map site is at the approximate center of the 0.25-square-mile area that contains these prospects and is accurate within 0.1 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 C-6(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

Tongass National Forest(National Forest)

National Forest FS(Type of land area)

FS(Federal land areas administered by FS)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary

Comments on the commodity information

  • Ore Material = Auriferous pyrite
  • Ore Material = Auriferous pyrite

Materials information

Materials Type of material
Gold Ore
Pyrite Ore
Quartz Gangue

Alteration

  • (Local) Locally, the wallrocks adjacent to the veins are bleached and pyritized.

Mineral occurrence model information

Model code 273
USGS model code 36a
Deposit model name Low-sulfide Au-quartz vein
Mark3 model number 27

Host and associated rocks

  • Host or associated Host
    Rock type Metamorphic Rock > Schist

Nearby scientific data

(1) -131.99568, 55.64474
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The country rocks near this site are marine, andesitic and basaltic metavolcanic rocks that are gradationally interbedded with flyschlike metasedimentary rocks (Berg and others, 1988, p. 18). The strata were regionally metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time (Brew, 1996, p. 27). The depositional age of the strata is uncertain. Berg and others (1998, p. 17) report that they closely resemble Upper Jurassic to mid-Cretaceous marine strata nearby on Gravina Island. ? According to Maas and others (1995, p. 183-184 and fig. 46), the deposits at the Snowstorm, Beulah, and, presumably, the Last Chance (Helm Bay) prospects consist of quartz vein swarms or stringer lodes in hornblende metadiorite. The veins carry auriferous pyrite, which in places is also disseminated in bleached wallrock adjacent to the veins. Maas and others (1995, table 25) report the following average metal contents in their samples from these deposits. Snowstorm: 1.20 ppm Au, 0.06 ppm Ag, 33 ppm Cu, 3.1 ppm Pb, and 9 ppm Zn. Beulah: 0.62 ppm Au, 0.16 ppm Ag, 30 ppm Cu, 6.3 ppm Pb, and 25 ppm Zn. Au and Cu values at the last Chance respectively were up to 16 ppb and 101 ppm. ? Fluid inclusion studies of quartz vein material from several of the Helm Bay lodes suggest that the veins formed at temperatures and pressures consistent with conditions during the Late Cretaceous greenschist-grade regional metamorphism (Maas and others, 1995, p. 184).
  • Age = Late Cretaceous.

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 = There are two adits, six feet long and three feet long, on the Snowstorm prospect; a 63-foot adit on the Last Chance prospect; and a 63-foot adit in the Beulah prospect (Maas and others, 1995, table 26). All of the workings date from the early 1900s.

Reference information

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.

  • Deposit

    Brew, D.A., 1996, Geologic map of the Craig, Dixon Entrance, and parts of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2319, 53 p., 1 sheet, scale 1:250,000.

Comments on the references

  • Primary Reference = Maas and others, 1995

General comments

Subject category Comment text
Deposit Model Name = Low-sulfide gold-quartz veins (Cox and Singer, 1986; model 36a)

Reporter information

Type Date Name Affiliation Comment
Reporter 30-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

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.