Sample: Snyder_1959_11
| Sample ID: | Snyder_1959_11 [1] |
| Station ID: | Snyder_1959_11 |
| AT Num: | |
| Volcano: | Little Sitkin |
| Possible source: | |
| Eruption: | |
| Collector: | Snyder, G. L. |
| Date sampled: | |
| Sample type 1: | Lava |
| Color: | brownish gray |
| Final unit: | |
| Text Description: | High-silica dacite of the Double Point dacite. Color: brownish gray (5 YR 5/l). Texture: hypocrystalline, porphyritic with feldspar phenocrysts as much as 3 mm long. Zoned and twinned plagioclase, 25-30 percent, varies in composition from An35 to An45 and averages An40. Accessory minerals are euhedral orthopyroxene, 2 percent; subhedral clinopyroxene, 2 percent; magnetite, 1 percent; and tridymite, 1 percent. The fluidal glassy to cryptocrystalline groundmass carries pyroxene, magnetite and plagioclase microlites. The plagioclase microlites have an average composition of An43. |
| Sample Location: |
References Cited
[1] Geology of Little Sitkin Island, Alaska, 1959
Snyder, G. L., 1959, Geology of Little Sitkin Island, Alaska: in Investigations of Alaskan volcanoes, U.S. Geological Survey Bulletin 1028-H, p. 169-210, 1 plate, scale 1:20,000.
full-text PDF 2 MB
plate 23 PDF 7 MB