Sample: 54-F-57
| Sample ID: | 54-F-57 [1] |
| Station ID: | 54-F-57 |
| AT Num: | |
| Volcano: | Makushin |
| Possible source: | |
| Eruption: | |
| Collector: | Fraser, G. D. |
| Date sampled: | 1954-01-01 |
| Sample type 1: | Lava |
| Color: | |
| Final unit: | |
| Text Description: | Olivine-bearing basalt porphyry from Makushin basalt and andesite, 2 1/2 miles southwest of Pakushin Cone. It is pale purple to medium light gray and contains plagioclase, pyroxene, and olivine phenocrysts 1-2 millimeters long. Phenocrysts compose 15 percent of the rock: 9 percent labradorite, which forms euhedral to subhedral stubby crystals having normal and oscillatory zones; 2 percent subhedral augite(?); 3 percent anhedral olivine with augite(?) reaction rims ; 1 percent subhedral to anhedral and embayed magnetite(?). The groundmass has crudely trachytic to intergranular texture and includes abundant subhedral laths and stubby crystals of calcic labradorite, much granular augite(?); a trace of a granular opaque mineral, and a trace of cristobalite(?). Alteration is slight; olivine and magnetite(?) 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