Bonanza Creek

Site Name

Primary: Bonanza Creek

---

Commodity

Primary: Gold
Secondary: Arsenic
Secondary: Copper
Secondary: Zinc

---

Location

State: Alaska
District: Circle

---

Land Status

Not available

---

Holdings

Not available

---

Workings

Not available

---

Ownership

Not available

---

Production

Not available

---

Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Unknown
Years of Production:
Organization:
Significant:

---

Physiography

Not available

---

Mineral Deposit Model

Model Name: Placer Au-PGE

---

Orebody

Not available

---

Structure

Not available

---

Alterations

Alteration Type: L
Alteration Text: 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).

---

Rocks

Not available

---

Analytical Data

Not available

---

Materials

Ore: Gold

---

Comments

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

Comment (Exploration): Status = Inactive

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

Comment (Reference): Primary Reference = Yeend, 1991; Freeman and others, 1988.

Comment (Workings): 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).

Comment (Geology): 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.

---

References

Reference (Deposit): Bundtzen, T.K., Swainbank, R.C., Clough, A.H., Henning, M.W., and Charlie, K.M., 1996, Alaska's mineral industry, 1995: Alaska Division of Geological and Geophysical Surveys Special Report 50, 72 p.

Reference (Deposit): Smith, P.S., 1933, Mineral industry of Alaska in 1930: U.S. Geological Survey Bulletin 836, p. 1-83.

Reference (Deposit): Lampright, R.L., 1996, Gold placer deposits near Fairbanks Alaska: Iron Fire Publications, Nederland, Colorado, 135 p.

Reference (Deposit): Smith, P.S., 1932, Mineral industry of Alaska in 1929, in Smith, P.S., and others Mineral resources of Alaska, report on progress of investigations in 1929: U.S. Geological Survey Bulletin 824-A, p. 1-81.

Reference (Deposit): Smith, P.S., 1936, Mineral industry in Alaska in 1934: U.S. Geological Survey Bulletin 868-A, p. 1-91.

Reference (Deposit): Yeend, W.E., 1991, Gold placers of the Circle district, Alaska - past, present, and future: U.S. Geological Survey Bulletin 1943, 42 p.

Reference (Deposit): Smith, P.S., 1934, Mineral industry of Alaska in 1933: U.S. Geological Survey Bulletin 864-A, p. 1-94.

Reference (Deposit): Mertie, J.B., Jr., 1932, Mining in the Circle district: U.S. Geological Survey Bulletin 824, p. 155-172.

Reference (Deposit): Smith, P.S., 1934, Mineral industry of Alaska in 1932: U.S. Geological Survey Bulletin 857-A, p. 1-91.

Reference (Deposit): Eakins, G.R., Jones, B.K. and Forbes, R.B., 1977, Investigation of Alaska's uranium potential: Alaska Division of Geological and Geophysical Surveys Open-File Report 109, 213 p., 10 sheets, scale 1:40,000.

Reference (Deposit): Menzie, W.D., Foster, H.L., Tripp, R.B., and Yeend, W.E., 1983, Mineral resource assessment of the Circle quadrangle, Alaska: U.S. Geological Survey Open-File Report 83-170-B, 61 p., 1 sheet, 1:250,000.

Reference (Deposit): Metz, P.A., 1991, Metallogeny of the Fairbanks mining district, Alaska and adjacent areas: University of Alaska, Fairbanks, Mineral Industry Reserarch Laboratory Report No. 90, 370 p.

Reference (Deposit): Freeman, C.J., Adams, D.D., Balla, J.C., and Metz, P.A., 1988, Circle joint venture 1988 final report: Fairbanks, Alaska, Fairbanks Exploration Inc. 23 p.

Reference (Deposit): Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Circle quadrangle, Alaska: U.S. Geological Survey Open-File Report 76-633, 72 p.

Reference (Deposit): Mertie, J.B., Jr., 1938, Gold placers of the Fortymile, Eagle, and Circle districts, Alaska: U.S. Geological Survey Bulletin 897-C, p. 133-261.

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Circle quadrangle, Alaska: U.S. Geological Survey Misc. Field Studies Map MF-391, 1 sheet, scale 1:250,000.

Reference (Deposit): Smith, P.S. 1939, Mineral industry in Alaska in 1937: U.S. Geological Survey Bulletin 910-A, p. 1-113.

Reference (Deposit): Smith, P.S., 1937, Mineral industry in Alaska in 1935: U.S. Geological Survey Bulletin 880-A, p. 1-95.

---

The Top Ten Gold Producing States

These ten states contributed the most to the gold production that built the West from 1848 through the 1930s. The Top Ten Gold Producing States.