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Bonanza Creek

Past Producer in Alaska, United States with commodities Gold, Arsenic, Copper, Zinc
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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 10001475
MRDS ID A012225
Record type Site
Current site name Bonanza Creek
Related records 10257503

Geographic coordinates

Geographic coordinates: -145.33184, 65.54862 (WGS84)
Relative position Bonanza Creek is a tributary to Porcupine Creek. The site of most placer mine activity extended approximately 1.5 miles upstream from the junction of Bonanza Creek and Porcupine Creek. This site includes both placer mining and mineralized schist.

Site location context

Political divisions (FIPS codes)

Yukon-Koyukuk(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Circle C-3(quadrangle 1:63,360 scale)

Circle NE(quadrangle 1:100,000 scale)

Circle C(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
Copper Secondary
Zinc Critical Secondary

Materials information

Materials Type of material
Gold Ore

Alteration

  • (Local) Sulfide mineralization in Bonanza Creek is largely restricted to graphitic and calcareous quartzites. The sample line along lower Bonanza Creek by Freeman and others (1988) indicates that sulfide minerals make up 10% of the rock. Sulfide mineralogy is dominated by subequal amount of pyrtie and arsenopyrite with rare chalcopyrite and sphalerite. Sulfide minerals occur as extremely fine-grained disseminations within the foliation of the schists. Late stage quartz veins commonly contain small amounts of pyrite or arsenopyrite. Iron oxides have formed after pyrite and pale green scorodite has formed after arsenopyrite. Local pale yellow stibiconite indicates the presence of antimony-bearing minerals (Freeman and others, 1988).

Mineral occurrence model information

Model code 119
USGS model code 39a
Deposit model name Placer Au-PGE
Mark3 model number 54

Host and associated rocks

  • Host or associated Host
    Rock type Unconsolidated Deposit > Gravel

Nearby scientific data

(1) -145.33184, 65.54862
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = Bonanza Creek, the main tributary of Porcupine Creek, is about 11 km long. Bedrock in the Bonanza Creek drainage is the Lower Schist unit described by Wiltse and others (1995) as a slightly calcareous quartz-muscovite schist, porphyroblastic-albite-quartz-chlorite-muscovite schist, and lesser amounts of quartzose porphyroblastic-albite-chlorite schist. This Bonanza Creek site includes both placer mining and mineralized schist.? A pebble count of gravel taken 3 km above the mouth of Bonanza Creek, shows a composition of 55 percent quartz-mica schist, 36 percent quartzite, and 9 percent quartz (Yeend, 1991). Zircon, garnet, ilmenite, pyrolusite, pyrrhotite, pyrite, and galena are present in the heavy mineral concentrates (Mertie, 1932). Gravel is 3 to 6 feet thick beneath 2 to 8 feet of muck, with a 75 to 150 feet wide paystreak in the lower valley (Mertie, 1938). Coarse gold, with considerable intergrown quartz, is located on bedrock and in cracks in the top 4 to 5 feet of the bedrock (Mertie, 1938). In the upper part of the creek, 6 feet of gravel lies on weathered bedrock with a pay streak 150 to 200 feet wide (Menzie and others, 1983, p.39). The largest nugget reported here was 1 ounce (Menzie and others, 1983, p.39).? Hydraulic mining with 2-inch nozzles was conducted in the 1930's (Mertie, 1938). Mining in the 1980's was confined to the middle and upper parts of Bonanza Creek. One to two meters of bedrock and one meter of overlying gravel was mined, and in places, the paystreak was over 60 meters wide. Exploratory drilling in the early 1980's in the gravel in the upstream part of the creek revealed sub-economic values (Yeend, 1991). Gold values in the gravel during the early mining years were 0.0375 to 0.05 ounces per cubic yard. The gold recovered was course and contained nuggets weighing as much as 10 ounces (Mertie, 1938). Fineness of gold varied little over a ten-year mining period (mean is 850 gold, 140 silver) (Mertie, 1938). In 1996, Paul and Company worked pay on Bonanza Creek , and Underwood Mining Co. tested a small paystreak at 114 Mile Steese Highway by washing about 50 cubic yards of gold-bearing gravel (Bundtzen and others, 1996).? Metz (1984) describes stratabound sulfide mineralization in the placer workings on the lower 3.2 km of Bonanza Creek. The mineralized section strikes east-west and dips to the north at 15 to 45 degrees. Channel samples taken at right angles to the compositional layering indicated gold grades of 0.12 ounces per ton over 1.5 meters. Stratabound mineralization?is cut by vertical quartz veinlets that range from less than a centimeter to 15 centimeters wide. The veinlets strike east-west and contain pyrite, arsenopyrite and gold. Gold wires up to 5 millimeters long and gold crystals up to 2 millimeters in diameter occur within vuggy quartz. Gold also occurs as inclusions in the arsenopyrite and along the sulfide grain boundaries (Metz, 1991, p. 108).? Freeman and others (1988), conducted detailed alteration mapping and channel-sampling along lower Bonanza Creek. This mapping revealed sulfide mineralization that is largely restricted to graphitic and calcareous quartzites. Subequal amounts of pyrite and arsenopyrite dominate the sulfide mineralogy, with rare chalcopyrite and sphalerite. Local pale yellow stibiconite indicates the presence of antimony-bearing minerals. Anomalous gold, silver and arsenic were reported in a metatuff unit that included disseminated arsenopyrite and pyrite. The highest gold value reported was 489 ppb.

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Circle

Comments on the production information

  • Production Notes = Mining has been reported (see workings/exploration); however, amount of production is unknown.

Comments on the workings information

  • Workings / Exploration = Hydraulic mining with 2-inch nozzles was conducted in the 1930's (Mertie, 1938). Mining in the 1980's was confined to the middle and upper parts of Bonanza Creek. One to two meters of bedrock and one meter of overlying gravel were mined, and in places the paystreak was over 60 meters wide. Exploratory drilling in the early 1980's in the gravel in the upstream part of the creek revealed sub-economic values (Yeend, 1991). Gold values in the gravel during the early mining years were 0.0375 to 0.05 ounces per cubic yard. The gold recovered was coarse and contained nuggets weighing as much as 10 ounces (Mertie, 1938). Fineness of gold varied little over a ten-year mining period (mean is 850 gold, 140 silver) (Mertie, 1938). In 1996, Paul and Company worked pay on Bonanza Creek , and Underwood Mining Co. tested a small paystreak at 114 Mile Steese Highway by washing about 50 cubic yards of gold-bearing gravel (Bundtzen and others, 1996).? In 1988, Fairbanks Exploration, Inc., conducted detailed alteration mapping and channel-sampling of the mineralized schist along lower Bonanza Creek (Freeman and others, 1988).

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Yeend, 1991; Freeman and others, 1988.

General comments

Subject category Comment text
Deposit Model Name = Placer gold deposit (Cox and Singer, 1986; model 39a), Disseminated and stratiform sulfides in schist; local gold-bearing quartz veinlets.

Reporter information

Type Date Name Affiliation Comment
Reporter 08-SEP-98 C.J. Freeman Avalon Development Corporation
Reporter 08-SEP-98 J.R. Guidetti Schaefer Avalon Development Corporation
Reporter 08-SEP-98 Clements, A.S. 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.