The most colorful of all may just be rainbow obsidian, which features an array of iridescent colors, including shades of green, purple, and blue. Colorful, sure, but we’d say it reminds us more ...

Rainbow Obsidian: Molten Earth To A Mesmerizingly Colorful Glassy Rock And if you go to California, you might even be able to find some for yourself. Holly Large. Holly Large.