"Taking one of these fragments, it had a black appearance and shiny surfaces quite similar to obsidian, a natural glass of ...

The tools were made from cooled-down lava called volcanic glass and were found at ... like blades and arrowheads. Well-crafted obsidian blades can be as sharp as surgical steel scalpels.

and smatterings of obsidian—black volcanic glass—that Paiute peoples once collected for arrowheads and jewelry. Scalding groundwater still bubbles to the surface in places. In such a landscape ...