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Sedanka Island; Biorka Prospect, Aleutians Mining District, Aleutians West Census Area, Alaska, USAi
Regional Level Types
Sedanka Island; Biorka ProspectProspect
Aleutians Mining DistrictMining District
Aleutians West Census AreaCensus Area
AlaskaState
USACountry

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Latitude & Longitude (WGS84):
53° 47' 30'' North , 166° 12' 0'' West
Latitude & Longitude (decimal):
Locality type:
KΓΆppen climate type:
Nearest Settlements:
PlacePopulationDistance
Unalaska4,491 (2017)23.9km
Dutch Harbor4,376 (2018)25.0km
Akutan1,040 (2017)47.0km


Location: Locality is 4 km south of Biorka Village, 0.9 km east of Udamat Bay on Sedanka Island. The locality corresponds to locality 3 of Cobb (1972, MF-446), it is accurate within about 300 m. It is also equivalent in part to anomaly no. 15 of Christie (1974).
Geology: Quartz and ankerite in nearly vertical veins in N 60oW striking fractures in diorite that forms hanging wall of fault that strikes N 80oE and dips 55oS. Richest mineralization near fault; fine-grained greenstone of footwall is barren. Veins contain sphalerite, abundant pyrite, a small amount of chalcopyrite and argentiferous(?) galena, and a small amount of gold. Pyrite also disseminated throughout diorite. Deposit along fault has been exposed for 70 m along strike, with mineralization zone a maximum of 18 m high and averaging more than 13 meters. Ore shoot extends at least 14 m beyond sampled zone, with fault traceable for at least 900 m west, and possibly 3.2 km east of mineralized zone, but no mineralization has been detected outside of the sampled area. Ores deposited at temperature below 138o C (Drewes and others, 1961, p. 658).
Workings: A 70 by 12 m area of tundra overburden was stripped by hydraulic methods and explosives, and 29 channel samples collected along strike of deposit for 75 m during USBM investigations in 1945 (Webber and others, 1946). Average analysis of 29 samples along narrow mineralized zone was 6.8 percent Zn. Average of 19 samples was 9.1 percent Zn, 0.24 percent Pb, 0.45 percent Cu, 0.04 oz/ton Au, 1.4 oz/ton Ag. Benefication tests showed that concentrates contained 0.3 percent Cd. Sampling in 1979 by Resource Associates of Alaska (Butherus, 1979) produced gold values ranging from 200 ppb to 12 ppm (0.348 oz/t). Christie (1974) did not visit the 'zinc' occurrence, however reconnaissance mapping in the area and limited sampling resulted in samples yielding up to 205 ppm copper, 1,000 ppm zinc, 3.1 ppm silver, and 0.34 ppm gold.
Alteration: Christie (1974) reports pervasive development of chlorite and minor sericite and quartz veinlets near diorite.

Commodities (Major) - Au, Ag, Cu, Zn; (Minor) - Cd, Pb
Development Status: No
Deposit Model: Polymetallic vein

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.


Mineral List


7 valid minerals.

Detailed Mineral List:

β“˜ Ankerite
Formula: Ca(Fe2+,Mg)(CO3)2
Reference: U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.
β“˜ Chalcopyrite
Formula: CuFeS2
Reference: U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.
β“˜ Galena
Formula: PbS
Reference: U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.
β“˜ Galena var. Silver-bearing Galena
Formula: PbS with Ag
Reference: U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.
β“˜ Gold
Formula: Au
Reference: U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.
β“˜ Pyrite
Formula: FeS2
Reference: U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.
β“˜ Quartz
Formula: SiO2
Reference: U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.
β“˜ Sphalerite
Formula: ZnS
Reference: U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
β“˜Gold1.AA.05Au
Group 2 - Sulphides and Sulfosalts
β“˜Chalcopyrite2.CB.10aCuFeS2
β“˜Galena2.CD.10PbS
β“˜var. Silver-bearing Galena2.CD.10PbS with Ag
β“˜Pyrite2.EB.05aFeS2
β“˜Sphalerite2.CB.05aZnS
Group 4 - Oxides and Hydroxides
β“˜Quartz4.DA.05SiO2
Group 5 - Nitrates and Carbonates
β“˜Ankerite5.AB.10Ca(Fe2+,Mg)(CO3)2

List of minerals for each chemical element

CCarbon
Cβ“˜ AnkeriteCa(Fe2+,Mg)(CO3)2
OOxygen
Oβ“˜ QuartzSiO2
Oβ“˜ AnkeriteCa(Fe2+,Mg)(CO3)2
MgMagnesium
Mgβ“˜ AnkeriteCa(Fe2+,Mg)(CO3)2
SiSilicon
Siβ“˜ QuartzSiO2
SSulfur
Sβ“˜ SphaleriteZnS
Sβ“˜ ChalcopyriteCuFeS2
Sβ“˜ Galena var. Silver-bearing GalenaPbS with Ag
Sβ“˜ PyriteFeS2
Sβ“˜ GalenaPbS
CaCalcium
Caβ“˜ AnkeriteCa(Fe2+,Mg)(CO3)2
FeIron
Feβ“˜ ChalcopyriteCuFeS2
Feβ“˜ AnkeriteCa(Fe2+,Mg)(CO3)2
Feβ“˜ PyriteFeS2
CuCopper
Cuβ“˜ ChalcopyriteCuFeS2
ZnZinc
Znβ“˜ SphaleriteZnS
AgSilver
Agβ“˜ Galena var. Silver-bearing GalenaPbS with Ag
AuGold
Auβ“˜ GoldAu
PbLead
Pbβ“˜ Galena var. Silver-bearing GalenaPbS with Ag
Pbβ“˜ GalenaPbS

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Bain, H.F., 1946, Alaska's minerals as a basis for industry: U.S. Bureau of Mines Information Circular 7379, 83 p. Berg, H.C., and Cobb, E.H., 1967, Metalliferous lode deposits of Alaska: U.S. Geological Survey Bulletin 1246, 254 p. Butherus, D.L., Gressitt, E.E., Pray, Jim, Corner, N.G., Lindberg, P.A., and Fankhauser, R.E., 1979, Exploration and evaluation of the Aleut Native Corporation Lands 1979: Unpublished Resource Associates of Alaska report prepared for Houston Oil and Minerals Corporation and available from The Aleut Corporation, 69 p., 1 appendix. Cobb, E.H., 1972, Metallic mineral resources map of the Unalaska quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies MF-446, 1 sheet, scale 1: 250,000. Drewes, Harold, Fraser, G.D., Snyder, G.L., and Barnett, H.F., Jr., 1961, Geology of Unalaska Island and adjacent insular shelf, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-S, p. 583-676. Randolph, D.B., 1991, Unalaska project, 1990 final report: Battle Mountain Exploration Company, Alaska District, 62 p., 5 appendices, 15 plates, various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.) Twenhofel, W.S., 1953, Potential Alaskan mineral resources for proposed electrochemical and electrometallurgical industries in the upper Lynn Canal area, Alaska: U.S. Geological Survey Circular 252, 14 p. Webber, B.S., Moss, J.M., and Rutledge, F.A., 1946, Exploration of Sedanka zinc deposit, Sedanka Island, Alaska: U.S. Bureau of Mines Report of Investigations 3967, 15 p.

Other Databases

Link to USGS - Alaska:UN005

Other Regions, Features and Areas containing this locality

North America PlateTectonic Plate
Pacific Ocean

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