As with other forms of obsidian, rainbow obsidian is both rock and glass ... but the nature of how it’s formed means that ...

Area tribes “all knew about it, all the archaeological sites in Montana that are important have some form or another of obsidian, and most of it comes from this place — Obsidian Cliff,” Dr ...

Hand-carved arrowheads and jagged spears made of obsidian, a sharp rock formed by volcanic magma, are remnants of vast prehistoric trade networks that once cut across western North America.

But dragonglass isn’t just found in Game of Thrones: It’s also scattered around Earth in the form of a volcanic rock called obsidian. It’s too bad Snow doesn’t have access to the mountains ...