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Alpha Ridge

Prospect in Alaska, United States with commodities Gold, Silver, Arsenic, Lead, Antimony, 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. Nearby scientific data
  10. Economic information about the deposit and operations
  11. Mining district
  12. Links to other databases
  13. Bibliographic references
  14. General comments
  15. Reporter information

Geologic information

Identification information

Deposit ID 10307979
Record type Site
Current site name Alpha Ridge

Geographic coordinates

Geographic coordinates: -165.52308, 64.62598 (WGS84)
Relative position The prospect is on the ridge between Alpha Creek (in the Nome C-1 quadrangle) and Sledge Creek, west tributaries to Snake River. Mineralization extends along the ridge for at least 1,000 feet between elevations of about 800 and 1,050 feet. The location is at the most intensely mineralized part of the prospect at an elevation of about 1,000 feet on the ridge and in the NW1/4 section 17, T. 10 S., R. 34 W., Kateel River Meridian. It is accurate within about 500 feet.

Site location context

Political divisions (FIPS codes)

Nome(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Nome C-2(quadrangle 1:63,360 scale)

Solomon NW(quadrangle 1:100,000 scale)

Nome(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Nome(hydrologic unit)

Norton Sound(hydrologic accounting unit)

Northwest(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Sitnasuak Native Corporation(ANCSA Village)

ANCSA Village NTVPIC(Type of land area)

NTVPIC(Federal land areas administered by NTVPIC)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Silver Secondary
Arsenic Critical Secondary
Lead Secondary
Antimony Critical Secondary
Zinc Critical Secondary

Materials information

Materials Type of material
Arsenopyrite Ore
Galena Ore
Gold Ore
Sphalerite Ore
Stibnite Ore
Albite Gangue
Ankerite Gangue
Quartz Gangue

Alteration

  • (Local) Albitization associated with the introduction of arsenopyrite and other metallic minerals in schist.

Mineral occurrence model information

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

Nearby scientific data

(1) -165.52308, 64.62598
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The Alpha Ridge prospect is an old prospect but its location was first reported by Sainsbury and others (1972 [OFR 72-321]). It was explored by Kennecott Exploration Company from 1990 to 1993. A series of soil samples collected in a reconnaissance survey were anomalous in arsenic, gold, and other elements. The reconnaissance survey was followed up with a detailed soil geochemical survey and trenching; about 1,000 feet of trenches were excavated with a trackhoe. Mineralization at the site is associated with highly albitized, arsenic-rich rocks and with massive quartz veins; the mineralization appears to be crudely stratabound (C.C. Hawley, Cindy Buxton, and D.L. Olson, written communication, 1992). The most intense mineralization is in an area about 300 by 300 feet on the crest of the ridge immediately below a saddle at an elevation of 1,040 feet. This saddle coincides with a high-angle fault of nearly east-west strike. To the east this fault trends toward the head of the placer gold deposit on Alpha Creek (NM196) in the Nome C-1 quadrangle. Maximum gold content found in the trench samples was 2,200 ppb; numerous samples contained more than 500 ppb gold and more than 10,000 ppm arsenic. Lead and zinc are also locally strongly enriched. The highest lead and zinc contents are associated with a massive, west-northwest-striking quartz vein that is exposed in a trench and in rubble about 300 feet north of the fault-controlled saddle. Lead values in galena and possibly as an oxidized mineral, are as high as 5,000 ppm in rock samples. Zinc, inferred to originally have been in sphalerite, is as high as 580 ppm. Antimony is consistently anomalous in the trench samples. The highest antimony value, 370 ppm, coincides with a gold value of 2,900 ppb. Although the main area of mineralization is below the strong fault which underlies the saddle at the south end of the prospect, areas of albitized rock with quartz float exist at least 1,000 feet north of the area of most intense mineralization. Grab samples from outlying areas locally contain more than 9,000 ppb gold. The auriferous area on Alpha Ridge almost certainly contributed placer gold to Sledge Creek (NM169), as well as to the Alpha Creek placer (NM196) in the Nome C-1 quadrangle. The prospect is near the crest of a major antiform, and country rock is the calcareous metaturbidite schist unit of Bundtzen and others (1994).
  • Age = Mid-Cretaceous; postdates regional metmorphism and may be similar in age to low-sulfide Au-quartz veins of the Nome district (see, for example, the Divide prospect, NM058).

Economic information about the deposit and operations

Development status Prospect

Comments on exploration

  • Status = Probably inactive

Mining district

District name Nome

Comments on the workings information

  • Workings / Exploration = About 1000 feet of trenches was excavated in 1991. An extensive soil geochemistry survey, part of a grid that extended from Monument Creek to Bangor Creek, was also completed between 1991 and 1993 by Kennecott Exploration Company. The prospect was probably originally located before 1920.

Reference information

Comments on the references

  • Primary Reference = This report

General comments

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

Reporter information

Type Date Name Affiliation Comment
Reporter 12-MAR-00 Hawley, C.C. and Hudson, Travis L. Hawley Resource Group

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.