Sample: 52-Sn-37
| Sample ID: | 52-Sn-37 [1] |
| Station ID: | 52-Sn-37 |
| AT Num: | |
| Volcano: | Kanaga |
| Possible source: | |
| Eruption: | |
| Collector: | Snyder, G. L. |
| Date sampled: | 1952-01-01 |
| Sample type 1: | Lava |
| Color: | |
| Final unit: | |
| Text Description: | Specimen 52-Sn-37 (Rittmann: dark rhyodacite) would be classified microscopically as vitrophyric labradorite dacite. This specimen is a dark-gray rock from the chill border of a small dike on northwest Kanaga. Its texture is porphyritic (~35 percent phenocrysts) with a hyalo-felty ground mass and strong flow structure. Phenocrystic plagioclase (<4 mm) is occasionally uniform, but usually shows either progressive or distinct oscillatory zoning. Composition ranges from An72-46, with most of the determinations about An54. A few of the crystals contain dusty zones of glassy inclusions. Augite (often as an overgrowth on hypersthene), hypersthene, opaque oxides, and rare ghost hornblende with a rim of granular pyroxene are also present as phenocrysts; small grains of cristohalite(?) are less conspicuous, and these are all set in a brown glass (n between 1.506 and 1.510) containing numerous plagioclase (An32-43) microlites. Potash, present in the analysis, is not expressed mineralogically and must be contained, along with occult quartz, in the low-index glass. |
| Sample Location: |
References Cited
[1] Geology of the Delarof and westernmost Andreanof Islands, Aleutian Islands, Alaska, 1959
Fraser, G. D., and Barnett, H. F., 1959, Geology of the Delarof and westernmost Andreanof Islands, Aleutian Islands, Alaska: in Investigations of Alaskan volcanoes, U.S. Geological Survey Bulletin 1028-I, p. 211-248, 4 sheets, scale 3 at 1:25,000, and 1 at 1:250,000.
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