Sample: 54-D-67
| Sample ID: | 54-D-67 [1] |
| Station ID: | 54-D-67 |
| AT Num: | |
| Volcano: | Table Top Mtn |
| Possible source: | |
| Eruption: | |
| Collector: | Drewes, Harald |
| Date sampled: | 1954-01-01 |
| Sample type 1: | Lava |
| Color: | |
| Final unit: | |
| Text Description: | Olivine basalt porphyry from a flow of Eider Point basalt 1 mile northeast of Tabletop Mountain. It is grayish red purple to medium gray and contains plagioclase phenocrysts as long as 1 mm. Phenocrysts compose 20 percent of the rock: 10 percent bytownite, which forms euhedral laths, stubby crystals, and fragments, and which has normal zones, apatite inclusions, and rare vermicular inclusions; 5 percent augite (?), which forms euhedral to subhedhral crystals and crystal clusters, and which has apatite inclusions; 5 percent subhedral to anhedral and embayed olivine. The groundmass has an intergranular texture, with stubby crystals and 25 percent vugs, and consists of abundant euhedral to subhedral plagioclase, much subhedral to granular augite(?) and a black opaque mineral, and a trace of olivine. Alteration is sparse; olivine and the black opaque mineral alter to hematite and limonite. |
| Sample Location: |
References Cited
[1] Geology of Unalaska Island and adjacent insular shelf, Aleutian Islands, Alaska, 1961
Drewes, Harald, Fraser, G. D., Snyder, G. L., and Barnett, H. F. Jr., 1961, Geology of Unalaska Island and adjacent insular shelf, Aleutian Islands, Alaska: in Investigations of Alaskan volcanoes, U.S. Geological Survey Bulletin 1028-S, p. 583-676, 3 sheets, scale 2 at 1:250,000 and 1 unknown.
full-text PDF 3.3 MB
plate 75 PDF 6.7 MB
plate 76 PDF 113 KB
plate 77 PDF 250 KB
table 1 PDF 326 KB