Myghapowit Mountain

Site Name

Primary: Myghapowit Mountain

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Commodity

Primary: Gold
Secondary: Silver
Secondary: Lead

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Location

State: Alaska
District: Bering Sea

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Land Status

Not available

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Holdings

Not available

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Workings

Not available

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Ownership

Not available

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Production

Not available

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Deposit

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

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Physiography

Not available

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Mineral Deposit Model

Not available

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Orebody

Not available

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Structure

Not available

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Alterations

Alteration Type: L
Alteration Text: The stock is altered to an assemblage of sericite, chlorite, clay minerals, and secondary silica. Only traces of the original textures are preserved in most places but breccia textures characterize several samples from the area (Patton and Csejtey, 1971, Table 1). The altered rocks are highly oxidized and well developed limonite staining and veining makes the stock conspicuously visible from a distance due to its red and orange color.

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Rocks

Not available

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Analytical Data

Not available

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Materials

Gangue: Limonite
Gangue: Pyrite
Gangue: Quartz

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Comments

Comment (Exploration): Status = Inactive

Comment (Reference): Primary Reference = Patton and Csejtey, 1971 (OFR 71-224)

Comment (Geology): Geologic Description = The 2 square mile, highly altered quatrz latite and latite stock is intruded along the east side of the Myghapowit pluton in east central St. Lawrence Island (Patton and Csejtey, 1971; Patton and Csejtey, 1980). About 1 mile of the northwest contact is with Mississippian limestone (Patton and Csejtey, 1971, Figure 3). The stock is altered to an assemblage of sericite, chlorite, clay minerals, and secondary silica. Only traces of the original textures are preserved in most places but breccia textures characterize several samples from the area (Patton and Csejtey, 1971, Table 1). The altered rocks are highly oxidized and well developed limonite staining and veining makes the stock conspicuously visible from a distance due to its red and orange color. Pyrite is the only sulfide mineral that has been identified in hand specimens. Fifteen grab samples of rocks and soils from the altered stock have low to moderately anomalous contents of several metals but most importantly show that gold is present in this mineralized system. All of the samples had detectable gold although only three were at levels at or above the 0.02 ppm dectection limit (0.2, 0.3. and 0.6 ppm, Patton and Csejtey, 1971, Table 1). One of these samples contained 3,000 ppm arsenic and 300 ppm antimony. In the fifteen samples, lead ranges from 30 to 3,000 ppm, copper from 5 to 150 ppm, molydenum from less than 5 to 700 ppm, bismuth from less than 10 to 300 ppm, tin from less than 10 to 150 ppm, and silver from less than 0.5 to 1 ppm. Three stream sediment samples, each from the upper part of a drainage headed against the altered stock, contain 150 ppm lead and 10 to 20 ppm molybdenum (Patton and Csejtey, 1972). Other elements were not anomalous in these stream sediment samples.

Comment (Deposit): Model Name = Gold in altered, hypabyssal, felsic intrusive rocks.

Comment (Geology): Age = Patton and Csejtey (1980) indicate that the altered stock is Cretaceous or Tertiary. There is no age control other than that it appears to intrude the Myghapowit pluton (mid-Cretaceous) and Mississippian limestone (Patton and Csejetey, 1980).

Comment (Workings): Workings / Exploration = Fifteen grab samples of rocks and soils from the altered stock have low to moderately anomalous contents of several metals but most importantly show that gold is present in this mineralized system. All of the samples had detectable gold although only three were at levels at or above the 0.02 ppm dectection limit (0.2, 0.3. and 0.6 ppm, Patton and Csejtey, 1971, Table 1). One of these samples contained 3,000 ppm arsenic and 300 ppm antimony. In the fifteen samples, lead ranges from 30 to 3,000 ppm, copper from 5 to 150 ppm, molydenum from less than 5 to 700 ppm, bismuth from less than 10 to 300 ppm, tin from less than 10 to 150 ppm, and silver from less than 0.5 to 1 ppm. Three stream sediment samples, each from the upper part of a drainage headed against the altered stock, contain 150 ppm lead and 10 to 20 ppm molybdenum (Patton and Csejtey, 1972). Other elements were not anomalous in these stream sediment samples.

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References

Reference (Deposit): Cobb, E.H., 1980, Summaries of data and lists of references to metallic and selected nonmetallic mineral deposits in fifteen quadrangles in southwestern and west-central Alaska: U.S. Geological Survey Open-File Report 80-909, 103 p.

Reference (Deposit): Patton, W.W., Jr., and Csejtey, Bela, Jr., 1971, Preliminary geologic investigations of eastern St. Lawrence Island, Alaska: U.S. Geological Survey, Open-File Report 71-224, 52 p.

Reference (Deposit): Patton, W.W., Jr., and Csejtey, Bela, Jr., 1980, Geologic map of St. Lawrence Island, Alaska: U.S. Geological Survey Miscellaneous Investigation Series Map I-1203, scale 1:250,000.

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Saint Lawrence quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-465, 1 sheet, scale 1:250,000.

Reference (Deposit): Patton, W.W., Jr., and Csejtey, Bela, Jr., 1972, Analyses of stream sediment and rock samples from St. Lawrence Island, Alaska, 1966-1971: U.S. Geological Survey Open-File Report 72-293, 78 p.

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