Polished mount backscatter electron image of a breadcrust bomb erupted from Great Sitkin on May 25, 2021. Image is 8.2 x 7.4 mm across. The top of the image captures the dense rind of a bomb while the vesicular interior is exposed along the bottom. Mineral phases include plagioclase (dark gray), pyroxenes (medium gray) and magnetite (white). Void spaces and vesicles are black. Rhyolitic glass forms interstitial spaces between mineral grains and is similar color to plagioclase. Trace amounts of apatite (light gray) and an SiO2 phase (dark gray and anhedral) are also visible. Images acquired on an JEOL 6510LV SEM at 20 kV, 12 mm working distance, spot size of 65, and in BEC imaging mode.
Image courtesy of AVO/USGS.
Please cite the photographer and the Alaska Volcano Observatory / U.S. Geological Survey when using this image.
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