Sample: 54-Sn-197
| Sample ID: | 54-Sn-197 [1] |
| Station ID: | 54-Sn-197 |
| AT Num: | |
| Volcano: | Makushin |
| Possible source: | |
| Eruption: | |
| Collector: | Snyder, G. L. |
| Date sampled: | 1954-01-01 |
| Sample type 1: | Countryrock |
| Color: | |
| Final unit: | |
| Text Description: | Granodiorite from north of the 3600 Mountain roof pendant, midway between Skan Ray and Naginak Cove. The texture is hypidiomorphic-granular. Felsic minerals compose 80-85 percent of the rock: 15-20 percent quartz, 10-15 percent orthoclase slightly altered to kaolin (<1 percent), and 50-55 percent plagioclase partially altered to sericite (1-2 percent). The plagioclase composition, by extinction angle, is An39 [mean of 40 crystals, standard deviation is 13 percent An, average amount of zoning per individual plagioclase crystal is 8 percent An per crystal], by index oils, is An40. Mafic minerals compose 15-20 percent: 5-8 percent actinolitic hornblende as long as 10 mm, 8-12 percent biotite up to 7 mm in diameter and partially altered to penninite (1-2 percent) and sphene (<1 percent, itself slightly altered to leucoxene <0.01 percent), 1-2 percent magnetite, and <0.01 percent apatite (in plagioclase) . |
| 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.
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table 1 PDF 326 KB