Gold Bench Mine, Koyukuk Mining District, Yukon-Koyukuk Census Area, Alaska, USAi
Regional Level Types | |
---|---|
Gold Bench Mine | Mine |
Koyukuk Mining District | Mining District |
Yukon-Koyukuk Census Area | Census Area |
Alaska | State |
USA | Country |
This page is currently not sponsored. Click here to sponsor this page.
Latitude & Longitude (WGS84):
66° 58' 51'' North , 150° 38' 13'' West
Latitude & Longitude (decimal):
Type:
KΓΆppen climate type:
Mindat Locality ID:
197668
Long-form identifier:
mindat:1:2:197668:0
GUID (UUID V4):
0b07af41-9d5c-4a6c-ac87-50ead1a6e395
Pleistocene bones are said to have been common in the gravels of Gold Bench (Reed, 1938). See also: Ironside Bench (BT004).
Location: Gold Bench is located on a prominent bend in the South Fork Koyukuk River about 1.2 miles upstream from the mouth of John R Creek. The mine is shown on the current (1970, photorevised 1975) Bettles D-2 topographic map. The placer is about 1000 feet wide and 0.8 mile long and covers an area of about 60 to 100 acres. The location is accurate.
Geology: Gold-bearing gravels occur in a high channel along the north side of the South Fork, Koyukuk River at Gold Bench. This high channel is about 30 feet higher than the present river channel. Maddren (1913) described the deposit as surficial, fine-washed stream gravels overlying other unconsolidated deposits. The gold-bearing gravels consist predominately of schist and quartz pebbles with lesser amounts of flint and igneous rocks. The most productive deposit was an 18- to 24-inch thick layer of gravel that covers an area of about 60 acres. The gold typically rested on a 2 - to 12-inch-thick layer of reddish sand, which acted as false bedrock. Small amounts of gold occurred throughout the gravel section (Maddren, 1913). Bedrock is decomposed to blue clay that probably was derived from shale (Reed, 1938). The depth to bedrock was estimated by Reed (1938) to be about 6 feet, although Maddren reported shafts to 20 feet deep that had not reached solid rock. The gold was generally fine, well worn and very flattened. Studies of panned samples in the 1950's described a variety of accessory minerals including magnetite, hematite, garnet, pyrite, chalcopyrite, cinnabar, rutile, cassiterite, scheelite, monazite, uranothorianite, galena, sphene, and possibly bismuthinite (Wedow and others, 1952; Nelson and others, 1954). Placer concentrates contain as much as 0.18 percent equivalent uranium. The source of the gold is not known. Maddren (1913) speculated that it might have come from the Tramway Bar (WI006) area on the Middle Fork, Koyukuk or, more likely, from the hills to the south. Cobb (1973 [B1374]) thought that at least some of the gold was probably from reworked glacial deposits. The deposit was mined mostly at the surface by hand methods. A few shafts were apparently sunk, but these produced little gold. Heiner and Wolff (1968) noted mining in the 1940's using heavy equipment. Grybeck (1977) indicated mining activity through 1975.
Workings: The deposit was mined mostly at the surface by hand. A few shafts were apparently sunk, but these produced little gold. Heiner and Wolff (1968) noted mining in the 1940's using heavy equipment. Grybeck (1977) indicated mining activity through 1975.
Age: Quaternary.
Production: Maddren (1913) reported that $150,000 (approximately 7,500 oz.) in gold was produced through 1909. Figures for later production are not known.
Commodities (Major) - Au; (Minor) - Bi(?), Cu, Hg, Pb, REE, Sn, Th, Ti, U, W
Development Status: Yes
Deposit Model: Placer Au (Cox and Singer, 1986; model 39a)
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsCommodity List
This is a list of exploitable or exploited mineral commodities recorded at this locality.Mineral List
13 valid minerals.
Detailed Mineral List:
β Bismuthinite ? Formula: Bi2S3 |
β Cassiterite Formula: SnO2 |
β Chalcopyrite Formula: CuFeS2 |
β Cinnabar Formula: HgS |
β Galena Formula: PbS |
β 'Garnet Group' Formula: X3Z2(SiO4)3 |
β Gold Formula: Au |
β Hematite Formula: Fe2O3 |
β Magnetite Formula: Fe2+Fe3+2O4 |
β 'Monazite' Formula: REE(PO4) |
β Pyrite Formula: FeS2 |
β Rutile Formula: TiO2 |
β Scheelite Formula: Ca(WO4) |
β Thorianite Formula: ThO2 |
β Thorianite var. Uranothorianite Formula: (Th,U)O2 |
β Titanite Formula: CaTi(SiO4)O |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
Group 1 - Elements | |||
---|---|---|---|
β | Gold | 1.AA.05 | Au |
Group 2 - Sulphides and Sulfosalts | |||
β | Chalcopyrite | 2.CB.10a | CuFeS2 |
β | Galena | 2.CD.10 | PbS |
β | Cinnabar | 2.CD.15a | HgS |
β | Bismuthinite ? | 2.DB.05 | Bi2S3 |
β | Pyrite | 2.EB.05a | FeS2 |
Group 4 - Oxides and Hydroxides | |||
β | Magnetite | 4.BB.05 | Fe2+Fe3+2O4 |
β | Hematite | 4.CB.05 | Fe2O3 |
β | Cassiterite | 4.DB.05 | SnO2 |
β | Rutile | 4.DB.05 | TiO2 |
β | Thorianite | 4.DL.05 | ThO2 |
β | var. Uranothorianite | 4.DL.05 | (Th,U)O2 |
Group 7 - Sulphates, Chromates, Molybdates and Tungstates | |||
β | Scheelite | 7.GA.05 | Ca(WO4) |
Group 9 - Silicates | |||
β | Titanite | 9.AG.15 | CaTi(SiO4)O |
Unclassified | |||
β | 'Monazite' | - | REE(PO4) |
β | 'Garnet Group' | - | X3Z2(SiO4)3 |
List of minerals for each chemical element
O | Oxygen | |
---|---|---|
O | β Cassiterite | SnO2 |
O | β Hematite | Fe2O3 |
O | β Magnetite | Fe2+Fe23+O4 |
O | β Monazite | REE(PO4) |
O | β Rutile | TiO2 |
O | β Scheelite | Ca(WO4) |
O | β Thorianite | ThO2 |
O | β Titanite | CaTi(SiO4)O |
O | β Thorianite var. Uranothorianite | (Th,U)O2 |
O | β Garnet Group | X3Z2(SiO4)3 |
Si | Silicon | |
Si | β Titanite | CaTi(SiO4)O |
Si | β Garnet Group | X3Z2(SiO4)3 |
P | Phosphorus | |
P | β Monazite | REE(PO4) |
S | Sulfur | |
S | β Bismuthinite | Bi2S3 |
S | β Chalcopyrite | CuFeS2 |
S | β Cinnabar | HgS |
S | β Galena | PbS |
S | β Pyrite | FeS2 |
Ca | Calcium | |
Ca | β Scheelite | Ca(WO4) |
Ca | β Titanite | CaTi(SiO4)O |
Ti | Titanium | |
Ti | β Rutile | TiO2 |
Ti | β Titanite | CaTi(SiO4)O |
Fe | Iron | |
Fe | β Chalcopyrite | CuFeS2 |
Fe | β Hematite | Fe2O3 |
Fe | β Magnetite | Fe2+Fe23+O4 |
Fe | β Pyrite | FeS2 |
Cu | Copper | |
Cu | β Chalcopyrite | CuFeS2 |
Sn | Tin | |
Sn | β Cassiterite | SnO2 |
W | Tungsten | |
W | β Scheelite | Ca(WO4) |
Au | Gold | |
Au | β Gold | Au |
Hg | Mercury | |
Hg | β Cinnabar | HgS |
Pb | Lead | |
Pb | β Galena | PbS |
Bi | Bismuth | |
Bi | β Bismuthinite | Bi2S3 |
Th | Thorium | |
Th | β Thorianite | ThO2 |
Th | β Thorianite var. Uranothorianite | (Th,U)O2 |
U | Uranium | |
U | β Thorianite var. Uranothorianite | (Th,U)O2 |
Other Databases
Link to USGS - Alaska: | BT003 |
---|
Other Regions, Features and Areas containing this locality
North America PlateTectonic Plate
- Ruby DomainDomain
This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to
visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders
for access and that you are aware of all safety precautions necessary.