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Grant

Past Producer in Alaska, United States with commodities Gold, Silver, Lead, Antimony, Tungsten
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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. Host and associated rocks
  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 10308826
MRDS ID A015285
Record type Site
Current site name Grant
Related records 10232761, 10002813

Geographic coordinates

Geographic coordinates: -147.95995, 64.88166 (WGS84)
Relative position The Grant mine is located in the SE1/4 sec. 28, T. 1 N., R. 2 W., Fairbanks Meridian. The Grant mine is marked on the Fairbanks D-2 topographic map on the southeast side of Ester Dome on the east side of Saint Patrick road. It is about 2.6 miles east of the top of Ester Dome and about three-quarters of a mile from the junction of the Saint Patrick road and the Ester Dome road. This mine is locality 21 of Cobb (1972 [MF 410]).

Site location context

Political divisions (FIPS codes)

Fairbanks North Star(Borough)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Fairbanks D-2(quadrangle 1:63,360 scale)

Big Delta NW(quadrangle 1:100,000 scale)

Fairbanks(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Silver Secondary
Lead Secondary
Antimony Critical Secondary
Tungsten Critical Secondary

Comments on the commodity information

  • Ore Material = antimony oxides

Materials information

Materials Type of material
Arsenic Ore
Arsenopyrite Ore
Galena Ore
Gold Ore
Scheelite Ore
Goethite Gangue
Muscovite Gangue

Alteration

  • The O'Dea vein-fault zone is heavily oxidized; it consists of gold-bearing quartz breccia cemented by iron, arsenic and antimony oxides, broken schist fragments, mylonite, and minor sulfides (Bundtzen and Kline, 1981).

Host and associated rocks

  • Host or associated Host
    Rock type
    Stratigraphic age (youngest) Proterozoic

Nearby scientific data

(1) -147.95995, 64.88166
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The Grant mine consists of two, structurally controlled, gold-bearing vein-fault deposits, hosted in polymetamorphic schist and quartzite: the Irishman zone (FB057) and the O'Dea zone. From December 1980 to June 1981, Bundtzen and Kline (1981) spent 25 days mapping the underground workings at the Grant mine, and the following is a summary of their work. At the Irishman vein-fault system, late-stage silica injection was accompanied by free gold, arsenopyrite, lead-antimony sulfosalts and rare scheelite. Ore fluids were emplaced along a fault zone trending sinuously N. 20-40 E. and dipping steeply to the southeast. On the 150-foot and 200-foot levels, the vein-fault dips from 58 to 72 degrees, but it flattens out to 15 to 35 degrees in raises above the 100-foot level, where it intersects incompetent graphite-muscovite schist. Vein widths vary from 3 to more than 22 inches and average about 13 inches wide on the 100-foot and 150-foot levels. By 1982, underground exploration and development had shown that the Irishman vein was more than 400 feet long and had not bottomed out in the lowest workings. The deposit probably continues beyond the southwest end of the ore body that has been explored, but the northeast end is cut by a north-northwest-striking joint-fault system. The O'Dea breccia zone consists of auriferous quartz breccia cemented by iron, arsenic, and antimony oxides, broken schist fragments, mylonite, and minor sulfides. The width of the vein-fault system varies from 6 inches to more than 6 feet. Multiple injections of silica also occurred along the O'Dea breccia zone, but unlike the Irishman system, recurrent movement along the vein-fault zone resulted in heavily oxidized, broken, and brecciated zones. The first recorded exploration at this site occurred in 1929, when lode gold mineralization was found at the bottom of an old shaft that was sunk for placer prospecting. The shaft was sunk through muck and gravel to bedrock which dipped east at a steep angle (Hill, 1933, p. 150). This original shaft was continued in bedrock to a depth of 240 feet and had 280 feet of drifts on the 200-foot and 240-foot levels. The 5- to 6-foot-wide quartz vein was said to strike N. 40 E. and dip 65 E. (Hill, 1933). Before 1931, approximately 500 to 600 tons of ore was milled from this vein. Exploration and development at the mine has been intermittent since the 1920's. Prior to 1950, about 6,000 tons of ore were mined from the Irishman vein (Eakins and others, 1985, p. 16). From 1979 to 1981, Tri-Con Mining, operator for Silverado Gold Mines, Ltd., at the Grant gold mine, engaged in an aggressive exploration and development program on the Irishman, O'Dea, and other gold-bearing shear zones on the Grant property (Eakins and others, 1985, p. 16). Underground workings consisted of 3,600 feet of drifts, crosscuts, and raises on and above the 200-foot level of the O'Dea zone (Bundtzen and Kline, 1981). During 1984, a $1.9 million exploration program was completed at the Grant mine (Eakins and others, 1985, p. 16). The drilling program defined an ore system on the O'Dea zone that extends 4,000 feet on strike and is as much as 1,000 feet deep. In 1985, the Grant mine recovered 1,563 ounces of gold and 1,178 ounces of silver from 5,036 tons of ore (Bundtzen and others, 1986, p. 26). During the seven weeks of mine production in 1989, the mill processed 8,000 tons which yielded 732 ounces of gold and 138 ounces of silver. From December 1987 to February 1989 when the mine closed, the Grant mine produced a total of 9,454 ounces of gold and 3,658 ounces of silver from 96,555 tons of ore at an average grade of 0.098 ounce of gold per ton (Bundtzen and others, 1990, p. 36-37).
  • Age = Gold-bearing quartz veins cut Fairbanks Schist host rocks that are considered to be pre-Devonian and probably Proterozoic in age (Newberry and others, 1996).

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Fairbanks

Comments on the production information

  • Production Notes = Prior to 1950, about 6,000 tons of ore were mined from the Irishman vein (Eakins and others, 1985, p. 16). In 1985, the Grant mine recovered 1,563 ounces of gold and 1,178 ounces of silver from 5,036 tons of ore (Bundtzen and others, 1986, p. 26). During the seven weeks of mine production in 1989, the mill processed 8,000 tons, which yielded 732 ounces of gold and 138 ounces of silver. From December 1987 to February 1989 when the mine closed, the Grant mine produced a total of 9,454 ounces of gold and 3,658 ounces of silver from 96,555 tons of ore at an average grade of 0.098 ounce of gold per ton (Bundtzen and others, 1990, p. 36-37). In early 1989, after the 100,000-ton tailings pond filled up at the Grant mine, the company decided that the costs for construction and permitting of a new tailings facility was prohibitive, and mining was shut down (Bundtzen and others, 1990, p. 37).

Comments on the reserve resource information

  • Reserves = The results of the 1990 ACNC drilling on a portion of the O'Dea vein system show a resource of 212,000 tons of material that contains 0.36 ounce of gold per ton (Swainbank and others, 1991, p. 11).

Comments on the workings information

  • Workings / Exploration = The first recorded exploration at this site occurred in 1929, when lode gold mineralization was found at the bottom of an old shaft that was sunk for placer prospecting. The shaft was sunk through muck and gravel to bedrock, which dipped east at a steep angle (Hill, 1933, p. 150). This original shaft was continued in bedrock to a depth of 240 feet and had 280 feet of drifts on the 200-foot and 240-foot levels. Exploration and development at the mine has been intermittent since the 1920's. From 1979 to 1981, Tri-Con Mining, operator for Silverado Gold Mines, Ltd., at the Grant gold mine, engaged in an aggressive exploration and development program on the Irishman, O'Dea, and other gold-bearing shear zones on the Grant property (Eakins and others, 1985, p. 16). Underground workings consisted of 3,600 feet of drifts and crosscuts and raises on and above the 200-foot level of the O'Dea zone (Bundtzen and Kline, 1981). The principal levels at the Irishman vein were at the 100-foot, 150-foot and 200-foot levels (Bundtzen and Kline, 1981). During 1984, a $1.9 million dollar exploration program was completed at the Grant mine (Eakins and others, 1985, p. 16). The drilling program defined an ore system on the O'Dea zone that extends 4,000 feet along strike and is as much as 1,000 feet deep. Late in 1989, Silverado Gold Mines, Ltd., signed an option agreement with American Copper and Nickel (ACNC) to explore and develop Silverado mining properties on Ester Dome, including the Grant mine property (Bundtzen and others, 1990, p. 37). In 1990, ACNC drilled 17,434 feet of core in the O'Dea vein system and on the Ethel vein system 2,000 feet to the north (Swainbank and others, 1991). ACNC also conducted an aerial geophysical survey of the area that same year (Bundtzen and others, 1991).

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Bundtzen and Kline, 1981

General comments

Subject category Comment text
Deposit Model Name = Structurally controlled, auriferous vein-fault deposit hosted in polymetamorphic schist and quartzite.

Reporter information

Type Date Name Affiliation Comment
Reporter 31-JUL-2001 J.R. Guidetti Schaefer and C.J. Freeman Avalon Development Corporation

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.