because it started out as silica-rich magma, eventually erupting as a viscous surface lava flow. This molten earth origin is what classes rainbow obsidian as an igneous rock. Lava destined to ...

Before we get into the snowflakes, obsidian is formed when rhyolitic magma (viscous molten rock with high concentrations of silica, but low levels of water and gas) quickly cools into a solid ...