obsidian

One gem is thought to be a rare, 2nd Century head of the Greek hero Hercules made from obsidian, a type of volcanic glass.

And it comes in four newly named colors: obsidian, porcelain, bay and aloe.

The Cahuilla also charted trade corridors reaching from the Colorado River to the shores of the Pacific, where coastal tribes traded shell jewelry for obsidian tools and animal skins from the interior.

As she sorted through thousands of shattered greenstones, seashells, and obsidian pieces, she noticed something peculiar.

We plodded through an obsidian darkness, one deliberate step at a time, our headlamp beams illuminating the way.