Sample: specimen 4
| Sample ID: | specimen 4 [1] |
| Station ID: | specimen 4 |
| AT Num: | |
| Volcano: | |
| Possible source: | |
| Eruption: | |
| Collector: | Unknown, Unknown |
| Date sampled: | 1952-01-01 |
| Sample type 1: | Lava |
| Color: | |
| Final unit: | |
| Text Description: | Analyzed specimen no. 4 is coarse-grained gabbro from a sill (?) 500 yards south of the head of Chapel Cove, Bay of Waterfalls. It is a bytownite-labradorite olivine gabbro with abundant magnetite. Small chips of the rock can be picked up with a pocket magnet. Dark minerals occur in single crystals or as clusters as great as 1 cm in diameter, but usually less than 5 mm. These dark constituents are set in a finer (less than 3 mm) matrix of feldspar laths. Feldspars are subhedral and the clinopyroxene generally anhedral. An estimated mode gives the following volume percents : zoned bytownite-labradorite, 65 percent; clinopyroxene, 15 percent; magnetite, 7 percent; olivine pseudomorphs (antigorite?), 8 percent; interstitial and pseudomorphic penninite and carbonate, 5 percent. |
| Sample Location: |
References Cited
[1] Geology of southern Adak Island and Kagalaska Island, Alaska, 1959
Fraser, G. D., and Snyder, G. L., 1959, Geology of southern Adak Island and Kagalaska Island, Alaska: in Investigations of Alaskan volcanoes, U.S. Geological Survey Bulletin 1028-M, p. 371-408, 2 sheets, scale 1:125,000.
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