The most colorful of all may just be rainbow obsidian, which features an array of iridescent colors, including shades of ...

Through his Michigan Rockhounds site, social media groups and presentations each year, Wiedenbein has helped many hopeful rock ... obsidian is made. Because of its specific origin, Leland Blue ...

and blue. Colorful, sure, but we’d say it reminds us more of an oil spill than a rainbow. As with other forms of obsidian, rainbow obsidian is both rock and glass. However, this isn’t the same ...