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 ...

It’s far more badass, 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.