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Koyana Creek

Prospect in Alaska, United States with commodity Gold
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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 10308294
Record type Site
Current site name Koyana Creek

Geographic coordinates

Geographic coordinates: -163.66525, 64.56832 (WGS84)
Relative position Lode gold mineralization has been prospected for about 500 feet east of lower Koyana Creek. Koyana Creek is a small drainage that flows south to its mouth on Norton Sound, 2.6 miles east of Bluff. This is locality 22 of Cobb (1972, MF 445; 1978, OF 78-181).

Site location context

Political divisions (FIPS codes)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Solomon C-4 SE(quadrangle 1:24,000 scale)

Solomon NE(quadrangle 1:100,000 scale)

Solomon C(quadrangle 1:250,000 scale)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary

Materials information

Materials Type of material
Arsenopyrite Ore
Gold Ore
Quartz Gangue

Alteration

  • (Local) Quartz veining and sulfide dissemination; oxidation is probably present although not described. At the nearby Saddle prospect (SO175), alteration minerals in the host schist include plagioclase, chlorite, carbonate, white mica, biotite, titanite, and tourmaline.

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) -163.66525, 64.56832
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = Metasedimentary schist intercalated in Paleozoic marble forms the bedrock of lower Koyana Creek and exposures along the coast for several hundred feet east of its mouth. Gold-bearing mineralization was prospected here in the early 1900's (Collier and others, 1908). Three short adits and a shallow shaft were developed (Mulligan, 1971). Exposures at the face of a 30-foot-long adit showed an 8-inch-wide quartz vein, a foot-wide iron-stained gouge zone along the vein, and an arsenopyrite and pyrite in the vein and enclosing schist (Cathcart, 1922). The schist contains quartz segregations and boudins with oxidized iron-stained spots in addition to crosscutting, at least partly joint-controlled, quartz veins and veinlets. The latter locally contain both pyrite and arsenopyrite (Herried, 1965). The largest crosscutting quartz vein observed by Herried (1965) was 4 inches wide and 10 feet long. Seven grab and chip samples from this area contained 0.01 to 0.32 ounces Au per ton and 0.16 to 0.65 ounces Ag per ton (Herried, 1965). One composite chip sample of schist, collected every 10 feet over a distance of 700 feet, contained 0.07 ounces Au per ton. This prospect if probably similar to the nearby Saddle prospect (SO175). The Saddle prospect is known from the work of Ford (1993) and Ford and Snee (1996). A large gold and arsenic anomaly in soils led to its discovery. Gold-bearing quartz veins are localized in extensional joints in quartz-muscovite schist that strike easterly and dip moderately to the south. The veins are discontinuous and commonly less than 3 inches thick. Gold grades are irregularly distributed; vein intersections up to 3.3 feet across have contained up to 1.8 ounces Au per ton. Minerals identified in the veins include arsenopyrite, biotite, carbonate, chlorite, fluorite, marcasite, plagioclase, pyrite, pyrrhotite, quartz, titanite, and white mica. Alteration minerals in the host schist include plagioclase, chlorite, carbonate, white mica, biotite, titanite, and tourmaline. The white mica in the veins is muscovite and that in the host schist is phengite. A sample of vein white mica gave a Ar/Ar plateau age of 109.3 +/- 0.3 Ma and metamorphic white mica in the host schist gave Ar/Ar plateau ages of 122.6 +/- 0.4 Ma and 122.4 +/- 0.2 Ma (Ford and Snee, 1996). The host schist is similar to that at the nearby Bluff (SO135) and Swede Creek (SO133) lode prospects. This schist is a band intercalated in Paleozoic marble (Herried, 1965; Mulligan, 1971; Till and others, 1986). . This deposit is also probably mid-Cretaceous, the age of some other lode gold deposits on southern Seward Peninsula. The southern Seward Peninsula lode gold deposits formed as a result of mid-Cretaceous metamorphism (Apodoca, 1994; Ford, 1993, Ford and Snee, 1996; Goldfarb and others, 1997) that accompanied regional extension (Miller and Hudson, 1991) and crustal melting (Hudson, 1994). This higher temperature metamorphism was superimposed on high pressure/low temperature metamorphic rocks of the region.
  • Age = Mid-Cretaceous; white mica from quartz veins in the Koyana Creek area gave Ar/Ar plateau dates of 109.1 +/- 0.7 Ma and 109.6 +/- 0.2 Ma (Ford and Snee, 1996).

Economic information about the deposit and operations

Development status Prospect

Comments on exploration

  • Status = Active?

Mining district

District name Council

Comments on the production information

  • Production Notes = A few tons of ore were reported to have been sacked but it is not known if this was shipped (Smith and Eakin, 1911).

Comments on the workings information

  • Workings / Exploration = Three short adits and a shallow shaft are noted in the area (Mulligan, 1971). One of the adits was 30-feet long (Cathcart, 1922).

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Herried, 1965

General comments

Subject category Comment text
Deposit Model Name = Discontinuous, irregular to joint-contolled quartz veins and veinlets with dissemminated arsenopyrite and pyrite in metasedimentary schist; low sulfide-Au quartz vein (Cox and Singer, 1986; model 36a).

Reporter information

Type Date Name Affiliation Comment
Reporter 19-AUG-99 Travis L. Hudson Applied Geology

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

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Authoritative Alaska resources

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