Obsidian is dark-colored volcanic glass that formed when molten lava cooled quickly. About 2.5 million years ago, volcanic eruptions in the western Utah desert spewed out these volcanic rocks.
In Snowflake Obsidian, black obsidian contains white spots of radiating needle-shaped christobalite
(high-temperature quartz) crystals, resembling snowflakes.
In Mahogany Obsidian, black obsidian alternates with dark brown, red, and orange.
This obsidian was found in the Black Rock Desert in Utah.