Rainbow

Past Producer in Alaska, United States with commodities Gold, Silver, Arsenic, Lead, Zinc

Geologic information

Identification information

Deposit ID 10002251
MRDS ID A013153
Record type Site
Current site name Rainbow
Related records 10113128

Geographic coordinates

Geographic coordinates: -136.83768, 58.87778 (WGS84)
Relative position The Rainbow adit is essentially at tidewater, west of the mouth of Reid Inlet on Glacier Bay. The upper Rainbow prospect is at an elevation of about 1000 feet; it is almost on trend with the bearing of the lower Rainbow adit. The upper prospect has a latitude of about 58.8748 and longitude of 136.8343 The locations are accurate within 0.1 mile.
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Geographic areas

Country State
United States Alaska

Commodities

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

Comments on the commodity information

  • Ore Material = Gold (native)

Materials information

Materials Type of material
Arsenopyrite Ore
Galena Ore
Pyrite Ore
Sphalerite Ore
Gold Ore
Calcite Gangue
Quartz Gangue

Alteration

  • (Local) Alteration was not described specifically at the Rainbow. In general for the Reid Inlet area, Rossman (1959, p. 43) says that the vein walls are altered for up to 10-15 feet from the veins. Oxidation formed a rust-red color, consistent with either sulfides or ankerite disseminated in the altered zone. MacKevett and others (1971, p. 59) noted abundant secondary iron minerals, gouge, and scattered free gold in the altered vein zones.

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 Plutonic Rock > Mafic Intrusive Rock > Diorite

Nearby scientific data

(1) -136.83768, 58.87778

Comments on the geologic information

  • Geologic Description = The Rainbow quartz (-calcite) fissure vein occurs in the part of the Reid Inlet gold area (Kimball and others, 1978) underlain by granodiorite of Cretaceous age (Rossman, 1959, B 1058-B; Brew and others, 1978). Minor amounts of alaskite are present near the mine (MacKevett and others, 1971, p. 59). The Rainbow vein-bearing fault zone strikes about N. 30 E., and dips 70 southeast to nearly vertical. The vein is narrow, generally 1 foot or less in thickness, but it is well mineralized. Arsenopyrite is common; galena and locally sphalerite are present up to a few percent each. Free gold is locally present. The vein was traced upslope for at least several hundred feet, and the vein-fault zone, nearly free of quartz, could be traced an additional 2000 feet up hill by subcropping bright red (hematitic?) altered rocks(Rossman, 1959, p.52). ? the mineralization is similar to the LeRoy mine(MF022), moderately abundant auriferous sulfides in a quartz-calcite rich vein matrix. Locally the vein was rich. MacKevett found some rich parts of the vein when he sampled the Rainbow adit in 1966 (MacKevett and others, 1971, p. 59-60, table 11). Three samples collected below overhand-stoped quartz veins in the adit contained from 1.518 to 10.208 ounces per ton gold. The richest sample also contained about 2 ounces per ton silver, 1000 ppm arsenic, 100 ppm copper, 15 ppm molybdenum, 500 ppm lead, and 2000 ppm zinc. All the mineralized samples had trace amounts of molybdenum. (Bismuth, antimony, and tungsten were looked for but not found). Major elements contained in the veins include calcium up to 2 percent and magnesium up to 0.8 percent , along with iron, suggesting the possiblity of ankerite or dolomite in the gangue.
  • Age = Late Cretaceous or younger.

Economic information

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Juneau

Comments on the production information

  • Production Notes = Based on narrow vein, tonnage small, but likely multiounce per ton gold.

Comments on the reserve resource information

  • Reserves = There is a resource present in the floor of the adit that could be developed with a winze. The winze would be below sea level. Inflows are uncertain but might be manageable with an adequate pillar. Reserves could likely be developed by continuing the drift. Rossman's (1959) mapping suggests the existence of vein intersections that could be targets for wider mining zones.

Comments on the workings information

  • Workings / Exploration = An adit was driven on the vein just above tide level for an estimated 190 feet. The vein was further developed by two raises and an overhand stope above adit level. Mining was in conjunction with the LeRoy vein (MF022) by the LeRoy Mining Co. The ore was hauled by barge and truck to the LeRoy mill. Shallow surface workings on the Upper Rainbow are at an elevation of about 1000 feet. Rossman mapped several veins of various strikes close to the Rainbow (Rossman, 1959, pl. 4).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A013153
USGS Alaska Resource Data File ARDF MF027

Bibliographic references

  • Deposit

    Rossman, Darwin, 1959, Geology and ore deposits in the Reid Inlet area, Glacier Bay, Alaska: U.S. Geological Survey Bulletin 1058-B, p. 33-58.

  • Deposit

    MacKevett, E.M., Jr., Brew, D.A., Hawley, C.C., Huff, L.C., and Smith, J.G., 1971, Mineral resources of Glacier Bay National Monument, Alaska: U.S. Geological Survey Professional Paper 632, 90 p., 12 plates, scale 1:250,000.

  • Deposit

    Brew, D.A., Johnson, B.R., Grybeck, D., Griscom, A., Barnes, D.F., Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources of the Glacier Bay National Monument Wilderness Study Area, Alaska: U.S. Geological Survey Open-File Report 78-494, 670 p.

  • Deposit

    Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources, in Brew, D. A., and others, Mineral resources of the Glacier Bay National Monument wilderness study area, Alaska: U.S. Geological Survey Open-File Report 78-494, p. C1-C375.

Comments on the references

  • Primary Reference = Rossman, 1959 (B 1058-B); MacKevett and others, 1971; Kimball and others, 1978

General comments

Subject category Comment text
Deposit Model Name = Low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a).
Deposit Other Comments = the mine is in Glacier Bay National Park and Preserve.

Reporter information

Type Date Name Affiliation Comment
Reporter 08-APR-99 Hawley, C.C. Hawley Resource Group