A compound is a substance that contains two or more elements close elementA pure substance that is made from only one type ... quickly. Obsidian is an example of an extrusive igneous rock.

As with other forms of obsidian, rainbow obsidian is both rock and glass ... 20 million years ago – and the same goes for other types of obsidian too. That’s because obsidian is pretty ...

Of note is that both Nch’kay and Kingcome obsidian, while highly valued, would have been harder to work with since the glass has small inclusions (called “phenocrysts”) that make it more difficult to ...