Prospect in Alaska, United States with commodities Silver, Gold, Copper, Lead, Zinc

Geologic information

Identification information

Deposit ID 10000700
MRDS ID A011332
Record type Site
Current site name Riverside

Geographic coordinates

Geographic coordinates: -149.61283, 63.23958 (WGS84)
Relative position The prospect is on the south bank of the West Fork Chulitna River, just upstream from the mouth of Bryn Mawr Creek. It is located in sec. 26, T.19 S., R. 11 W., of the Fairbanks Meridian. Accuracy is within 0.5 miles.?This is location 7 of Cobb (1978: OFR 78-1062).
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Geographic areas

Country State
United States Alaska


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

Materials information

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


  • (Local) Narrow phyllic alteration haloes around and in porphyry dikes typically consists of sericite, quartz, and pyrite. In addition, skarn alteration minerals are garnet, pyroxene, and epidote.

Mineral occurrence model information

Model code 59
USGS model code 18b
Deposit model name Skarn Cu
Mark3 model number 8
Model code 85
USGS model code 22c
Deposit model name Polymetallic veins
Mark3 model number 46

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone
    Stratigraphic age (youngest) Late Triassic

Nearby scientific data

(1) -149.61283, 63.23958

Comments on the geologic information

  • Geologic Description = The country rocks in the area of the Riverside prospect are Triassic, redbed sandstone, conglomerate and limestone that have been intruded by a hornblende-quartz diorite dike. The deposit is in hornfelsed bedded rocks and consists chiefly of quartz-sulfide veins, and stockworks, and of sulfide disseminations. The sulfide minerals are arsenopyrite, chalcopyrite, galena, pyrite, pyrrhotite, and sphalerite. Small, sulfide-bearing skarn deposits are in marble adjacent to the dike (unpublished report by Addwest Minerals International Ltd., 1997). Samples contain 0.02 to 0.72 ounce of gold per ton and 0.3 to 2.10 ounces of silver per ton (Ross, 1933). The relatively high gold and silver values may be due to supergene enrichment. A fault may truncate the deposit to the south. The Riverside deposit is similar in mineralogy and type to other deposits satellitic to the Golden Zone deposit (HE043).
  • Age = Late Cretaceous (70 -65 Ma), assuming that the deposit is satellitic to the Golden Zone deposit (HE043).

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Active

Mining district

District name Valdez Creek

Comments on the workings information

  • Workings / Exploration = Mainly surface workings. There are reports of a 10-foot tunnel and 15-foot shaft that are now caved. Recent geochemical exploration has identified a broad soil anomaly that outlines the deposit. Samples contain 0.02 to 0.72 ounce of gold per ton and 0.3 to 2.10 ounces of silver per ton (Ross, 1933).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A011332
USGS Alaska Resource Data File ARDF HE033

Bibliographic references

  • Deposit

    Townsend, H.H., 1925, Assay returns: Alaska Territorial Dept. of Mines Itinerary Report 195-48, 4 p.

  • Deposit

    Ross, C.P., 1933, The Valdez Creek mining district, Alaska: U.S. Geological Survey Bulletin 849, p. 289-467.

  • Deposit

    Berg, H.C., and Cobb, E.H., 1967, Metalliferous Lode Deposits of Alaska. U.S. Geological Survey Bulletin 1246, 254 p.

  • Deposit

    Hawley, C.C., and Clark, A.L., 1974, Geology and mineral deposits of the upper Chulitna district, Alaska: U.S. Geological Survey Professional Paper 758-B, p. 1-47, 2 sheets, scale 1:12,000 and 1:48,000.

  • Deposit

    Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Healy quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-1062, 113 p.

  • Deposit

    Hawley, C.C., and others, 1978, Mineral appraisal of lands adjacent to Mt. McKinley National Park, Alaska. Contract No. JO166107: U.S. Bureau of Mines Open-File Report 24-78, 274 p., 12 sheets.

  • Deposit

    Capps, S.R., 1919, Mineral resources of the upper Chulitna region: U.S. Geological Survey Bulletin 692-D, p. 207-232.

Comments on the references

  • Primary Reference = Hawley and Clark, 1974

General comments

Subject category Comment text
Deposit Model Name = Cu skarn; Polymetallic veins (Cox and Singer, 1986; models 18b, 22c)
Deposit Model Number = 18b, 22c

Reporter information

Type Date Name Affiliation Comment
Reporter 07-APR-2000 N. Van Wyck Stevens Exploration Management Corporation