Sample: Snyder_1959_6
| Sample ID: | Snyder_1959_6 [1] |
| Station ID: | Snyder_1959_6 |
| AT Num: | |
| Volcano: | Little Sitkin |
| Possible source: | |
| Eruption: | |
| Collector: | Snyder, G. L. |
| Date sampled: | |
| Sample type 1: | Lava |
| Color: | medium gray |
| Final unit: | |
| Text Description: | Low-silica dacite of Little Sitkin dacite. Color: medium gray (N 5). Texture: hypocrystalline, massive. Plagioclase, 20 to 25 percent, ranges in composition from An55 to An72; a few have fritted centers. Orthopyroxene, 2-3 percent, and clinopyroxene, 2-3 percent, both distinctly pleochroic in light pink and light green; a few orthopyroxene and clinopyroxene centers in differently oriented clinopyroxene crystals. One relict olivine grain, with a thick reaction rim of pyroxene and magnetite. No oxyhornblende xenocrysts although this mineral is plentiful in nearby thin laminae of rhyodacite. Groundmass brownish glass filled with magnetite dust and crystallites. |
| 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