Photomicrograph of volcanic glass shard as seen in plane light at 20x magnification. The fluid-like structure of this shard is clear evidence that it was once a liquid with trapped gas bubbles. Glass shard from sample AT-039, USGS/Alaska Tephra Laboratory.
Image courtesy of AVO/USGS.Please cite the photographer and the Alaska Volcano Observatory / U.S. Geological Survey when using this image.
Full Resolution.