Obsidian is formed from quickly cooled lava, which is the parent material. Extrusive formation of obsidian may occur when felsic lava cools rapidly at the edges of a felsic lava flow or volcanic dome, or when lava cools during sudden contact with water or air.

Where is black obsidian found?

Obsidian can be found all over the world in areas with volcanic activity. For example, significant deposits of obsidian can be found in the United States, Canada, Mexico, Guatemala, Argentina, Chile, Greece, Hungary, Italy, Iceland, Russia, New Zealand, Japan, and Kenya.

Does obsidian form underground?

Seventy percent of obsidian rock is made of silica. ... The best obsidian is formed underground near a volcanic vent because those rocks will have limited impurities. Obsidian flows are so slow that often other obsidian flows will occur on top of each other causing a streaked appearance in the obsidian rock.