Counterclockwise from top: obsidian, pumice (lower left), and rhyolite (lower right)
Pig carved in snowflake obsidian, 10 centimeters (4 in) long. The markings are spherulites.
from Lake County, Oregon
A polished snowflake obsidian on a white background
A polished snowflake obsidian
Obsidian from Panum Crater, Mono Lake.
Obsidian talus at Obsidian Dome, California
Pile of obsidian on Newberry Obsidian flow, central Oregon
Glass Mountain, a large obsidian flow at Medicine Lake Volcano