Sample: P49Se4
| Sample ID: | P49Se4 [1] [2] |
| Station ID: | P49Se4 |
| AT Num: | |
| Volcano: | Semisopochnoi |
| Possible source: | |
| Eruption: | |
| Collector: | Powers, H. A. |
| Date sampled: | 1949-05-01 |
| Sample type 1: | Lava |
| Color: | |
| Final unit: | Pochnoi volcanics |
| Text Description: | Olivine basalt that is a porphyritic dense medium-gray (N 5) slightly vesicular rock, with intergranular texture. The phenocrysts consist of plagioclase, which averages about An85 (as determined by the average index of refraction); olivine (Fa32 as determined by the mean index of refraction), about 6 percent of the rock and ranging in length from 0.1 to 1 mm; and sparse augite, ranging from 0.1 to 0.25 mm. The groundmass is chiefly plagioclase, averaging An57; augite granules that are apparently pigeonitic, as shown by a 2V of 35o; magnetite; and intersertal brown glass, charged with minute magnetite granules. |
| 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.
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