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Sample: P49Se6

Sample ID: P49Se6 [1] [2]
Station ID: P49Se6
AT Num:
Volcano: Sugarloaf Peak
Possible source:
Eruption:
Collector: Powers, H. A.
Date sampled: 1949-01-01
Sample type 1: Lava
Color:
Final unit: Sugarloaf Head
Text Description: P49Se6 is from a very recent flow on the eastern shore (142,200' E., 269,550' N.), which Powers considered younger than the most recent eustatic bench, and which is unmantled by ash. Powers estimated the thickness at more than 20 feet, and notes that there was much copper staining. It is a dense medium-gray rock with conspicuous green augite phenocrysts. It is seriate, with an intergranular texture. The principal constituents are bytownite (An72), augite (Di70He38), and olivine (Fa35) as much as 1 mm in diameter, in part forming clots of small prisms, and magnetite. The groundmass augite is pleochroic from pale brown to pale green, has a 2V of 20°, and hence is rather pigeonitic. The augite phenocrysts also have thin pigeonitic outer zones.
Sample Location:

References Cited

[1] Geologic reconnaissance of Semisopochnoi Island, western Aleutian Islands, Alaska, 1959

Coats, R. R., 1959, Geologic reconnaissance of Semisopochnoi Island, western Aleutian Islands, Alaska: in Investigations of Alaskan volcanoes, U.S. Geological Survey Bulletin 1028-O, p. 477-519, 1 sheet, scale 1:25,000.
full-text PDF 1.4 MB
plate 59 PDF 2.7 MB

[2] Postglacial eruptive history and geochemistry of Semisopochnoi volcano, western Aleutian Islands, Alaska, 2018

Coombs, M.L., Larsen, J.F., and Neal, C.A., 2018, Postglacial eruptive history and geochemistry of Semisopochnoi volcano, western Aleutian Islands, Alaska: U.S. Geological Survey Scientific Investigations Report 2017-5150, 32 p., https://doi.org/10.3133/sir20175150.