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Colorado Gossan

Occurrence in Alaska, United States with commodities Gold, Arsenic, Mercury, Antimony
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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 10307770
Record type Site
Current site name Colorado Gossan

Geographic coordinates

Geographic coordinates: -155.97701, 63.56046 (WGS84)
Relative position The Colorado Gossan occurrence is located on a south-facing slope overlooking the broad saddle that contains the Montana Saddle prospect (MD018). The occurrence is at an elevation of 1,870 feet (570 m) in Section 28, T. 22 S., R. 15 E., of the Kateel River Meridian. The occurrence is precisely located as the reporter visited the site in 1996.

Site location context

Political divisions (FIPS codes)

Yukon-Koyukuk(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Medfra C-6(quadrangle 1:63,360 scale)

Medfra N(quadrangle 1:100,000 scale)

Medfra(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Arsenic Critical Secondary
Mercury Secondary
Antimony Critical Secondary

Comments on the commodity information

  • Gangue = Ferricrete

Materials information

Materials Type of material
Arsenopyrite Ore
Tourmaline Gangue

Alteration

  • (Local) Extensive oxidation of original sulfide mineralization.

Mineral occurrence model information

Model code 72
USGS model code 19a
Deposit model name Polymetallic replacement
Mark3 model number 47

Host and associated rocks

  • Host or associated Associated
    Rock type
    Stratigraphic age (youngest) Late Cretaceous
    Chronological age 71

Nearby scientific data

(1) -155.97701, 63.56046
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The Colorado Gossan is a rectangular shaped, 1,500 feet by 950 feet (457 m by 290 m) zone of iron rich ferricrete-tourmaline flooding in hornfels adjacent to the Cripple Creek Mountains pluton. Most of the zone is rubble crop with only a few outcrops observed. Disseminated arsenopyrite grains were seen in selected hand specimens but most samples are extensively oxidized. The gossan area is approximately 2,500 feet (762 m) away from the contact between the hornfels and plutonic phases of the Cripple Creek Mountains stock. The Colorado Gossan prospect is inferred to be Late Cretaceous based on 71.0 Ma age of adjacent plutonic rocks (Moll and others, 1981). Three large, continuous, chip-channel samples taken across 700 feet (213 m) of the long axis of the zone averaged 1,815 ppm arsenic, 80 ppb gold, 3,540 ppb mercury, and 154 ppm antimony (Bundtzen and others, 1997).
  • Age = the Colorado Gossan prospect is inferred to be Late Cretaceous based on 71.0 Ma age of adjacent plutonic rocks (Moll and others, 1981).
  • Age = Chronological age is for adjacent plutonic rocks.

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Inactive

Mining district

District name Innoko

Comments on the workings information

  • Workings / Exploration = No previous surface working were detected in 1996. Three large, continuous, chip-channel samples taken across 700 feet (213 m) of the long axis of the zone averaged 1,815 ppm arsenic, 80 ppb gold, 3,540 ppb mercury, and 154 ppm antimony (Bundtzen and others, 1997).

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Bundtzen and others, 1997

General comments

Subject category Comment text
Deposit Model Name = Polymetallic replacement deposit (Cox and Singer, 1986; model no. 19a)
Deposit Other Comments = Similar morphological features at Won-North prospect (MD021) and Win prospect (MD060).

Reporter information

Type Date Name Affiliation Comment
Reporter 03-JUN-98 Bundtzen, T.K. Pacific Rim Geological Consulting

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.