Ascension; Ibex Mine, Juneau Mining District, Juneau, Alaska, USAi
Regional Level Types | |
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Ascension; Ibex Mine | Mine |
Juneau Mining District | Mining District |
Juneau | City Borough |
Alaska | State |
USA | Country |
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Latitude & Longitude (WGS84):
58° 17' 6'' North , 134° 18' 54'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
Place | Population | Distance |
---|---|---|
Juneau | 32,756 (2017) | 6.4km |
Mindat Locality ID:
196326
Long-form identifier:
mindat:1:2:196326:0
GUID (UUID V4):
28eae353-ea7a-41bd-b11f-cb57dc649df9
Location: This mine is at an elevation of approximately 2,600 feet on the north side of Sheep Creek. It is 1/2 mile southwest of Sheep Mountain and 1/2 mile east of Roberts Peak, just south of the center of the boundary between sections 28 and 29, T. 41 S., R. 68 E. of the Copper River Meridian. The location is accurate.
Geology: The Ascension (Ibex) Mine was discovered in 1887 and was developed by 4 adits. An estimated 800 tons of ore was mined but production records are not available. The deposit consists of three boudinaged, concordant, quartz veins near the contact between black phyllite and green phyllite (Redman and others, 1989). The veins are up to 300 feet long, 1.5 feet thick, and contain chalcopyrite, galena, native gold, native silver, pyrrhotite, sphalerite, and tetrahedrite. The U.S. Bureau of Mines has estimated an inferred resource of 10,000 tons of ore with 3.44 ounces of silver and 0.01 ounce of gold per ton, with an average mining width of 3.0 feet (Redman and others, 1989). Their samples of the veins contained up to 354.6 ppm silver, 0.7 ppm gold, 0.54 percent lead, and 0.47 percent zinc. They also collected a 300-pound metallurgical sample that contained 382 ppm silver and 6.2 ppm gold. Cyanide amenability tests recovered 63.7 percent of the gold but only 1.1 percent of the silver (Redman and others, 1989). This prospect is in the Juneau Gold Belt, which consists of more than 200 gold-quartz-vein deposits that have produced nearly 7 million ounces of gold. These gold-bearing mesothermal quartz vein systems form a zone 160 km long by 5 to 8 km wide along the western margin of the Coast Mountains. The vein systems are in or near shear zones adjacent to west-verging, mid-Cretaceous thrust faults. The veins are hosted by diverse, variably metamorphosed, sedimentary, volcanic, and intrusive rocks. From the Coast Mountains batholith westward, the host rocks include mixed metasedimentary and metavolcanic sequences of Carboniferous and older, Permian and Triassic, and Jurassic-Cretaceous age. The sequences are juxtaposed along mid-Cretaceous thrust faults (Miller and others, 1994). The sequences are intruded by mid-Cretaceous to middle Eocene plutons, mainly diorite, tonalite, granodiorite, quartz monzonite, and granite. Sheetlike tonalite plutons emplaced just east of the Juneau Gold Belt and undeformed granite and granodiorite bodies that are emplaced farther to the east are between 55 and 48 Ma (Gehrels and others, 1991). The structural grain of the belt is defined by northwest-striking, moderately to steeply northeast-dipping, penetrative foliation that developed between Cretaceous and Eocene time (Miller and others, 1994). The majority of the veins in the Juneau Gold Belt strike northwest. Isotopic dates indicate that the auriferous veins in the Juneau Gold Belt formed between 56 and 55 Ma (Miller and others, 1994; Goldfarb and others, 1997).
Workings: The deposit at the Ascension (Ibex) Mine was discovered in 1887 and was developed by 4 adits.
Age: Isotopic dates indicate that the auriferous veins in the Juneau Gold Belt formed between 56 and 55 Ma (Miller and others, 1994; Goldfarb and others, 1997).
Production: An estimated 800 tons of ore was mined but production figures are not available.
Reserves: The U.S. Bureau of Mines has estimated an inferred resource of 10,000 tons of ore that contain 3.44 ounces of silver and 0.01 ounce of gold per ton, with an average mining width of 3.0 feet (Redman and others, 1989).
Commodities (Major) - Ag, Au, Pb, Zn; (Minor) - Cu
Development Status: Yes; small
Deposit Model: Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a)
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
7 valid minerals.
Detailed Mineral List:
ⓘ Chalcopyrite Formula: CuFeS2 |
ⓘ Galena Formula: PbS |
ⓘ Gold Formula: Au |
ⓘ Pyrrhotite Formula: Fe1-xS |
ⓘ Quartz Formula: SiO2 |
ⓘ Silver Formula: Ag |
ⓘ Sphalerite Formula: ZnS |
ⓘ 'Tetrahedrite Subgroup' Formula: Cu6(Cu4C2+2)Sb4S12S |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
Group 1 - Elements | |||
---|---|---|---|
ⓘ | Gold | 1.AA.05 | Au |
ⓘ | Silver | 1.AA.05 | Ag |
Group 2 - Sulphides and Sulfosalts | |||
ⓘ | Sphalerite | 2.CB.05a | ZnS |
ⓘ | Chalcopyrite | 2.CB.10a | CuFeS2 |
ⓘ | Pyrrhotite | 2.CC.10 | Fe1-xS |
ⓘ | Galena | 2.CD.10 | PbS |
ⓘ | 'Tetrahedrite Subgroup' | 2.GB.05 | Cu6(Cu4C2+2)Sb4S12S |
Group 4 - Oxides and Hydroxides | |||
ⓘ | Quartz | 4.DA.05 | SiO2 |
List of minerals for each chemical element
O | Oxygen | |
---|---|---|
O | ⓘ Quartz | SiO2 |
Si | Silicon | |
Si | ⓘ Quartz | SiO2 |
S | Sulfur | |
S | ⓘ Chalcopyrite | CuFeS2 |
S | ⓘ Galena | PbS |
S | ⓘ Pyrrhotite | Fe1-xS |
S | ⓘ Sphalerite | ZnS |
S | ⓘ Tetrahedrite Subgroup | Cu6(Cu4C22+)Sb4S12S |
Fe | Iron | |
Fe | ⓘ Chalcopyrite | CuFeS2 |
Fe | ⓘ Pyrrhotite | Fe1-xS |
Cu | Copper | |
Cu | ⓘ Chalcopyrite | CuFeS2 |
Cu | ⓘ Tetrahedrite Subgroup | Cu6(Cu4C22+)Sb4S12S |
Zn | Zinc | |
Zn | ⓘ Sphalerite | ZnS |
Ag | Silver | |
Ag | ⓘ Silver | Ag |
Sb | Antimony | |
Sb | ⓘ Tetrahedrite Subgroup | Cu6(Cu4C22+)Sb4S12S |
Au | Gold | |
Au | ⓘ Gold | Au |
Pb | Lead | |
Pb | ⓘ Galena | PbS |
Other Databases
Link to USGS - Alaska: | JU170 |
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