California Rainbow Obsidian Is a Natural Wonder (Amazing Photos)

On the Modoc National Forest, obsidian excavation may be done under a Free Use Authorization at any of the four designated mines. Excavation is allowed at these locations only. The Free Use Authorization allows a visitor to collect a predetermined amount per year of obsidian for their own personal use.(This rock had marvelous stripes of rich, vibrant color. photo: Scott's Rock & Gem)