Like other igneous rocks, the glossy glass originates from molten rock that has been spewed out from the bowels of the Earth via volcanoes.. Before we get into the snowflakes, obsidian is formed ...

This molten earth origin is what classes rainbow obsidian as an igneous rock. Lava destined to become obsidian cools rapidly once on the surface and, thanks to its viscous nature, ...

This molten earth origin is what classes rainbow obsidian as an igneous rock. Lava destined to become obsidian cools rapidly once on the surface and, thanks to its viscous nature, ...

Obsidian is an example of an extrusive igneous rock. Obsidian has crystals which are so small that they are impossible to see without a microscope. Intrusive.

Obsidian, a gemstone also known as volcanic glass, is widely distributed in the Southwest. It is an extrusive igneous rock comprised of feldspar and quartz, endemic to volcanic regions.

Unpolished, the igneous rock can look dusty gray or brown. But polished, it becomes pitch black and shiny—sometimes so shiny, you can sometimes see your own reflection . Obsidian from Yellowstone.