From the article: > Many of the tools were made from a black volcanic rock called obsidian, which was brought to the site and processed there. But from where?

From the article: > Many of the tools were made from a black volcanic rock called obsidian, which was brought to the site and processed there. But from where? There aren’t any obsidian outcrops near Olorgesailie. The chemistry of the tools suggests that they came from sources up to 100 kilometers away. But “these are straight-line distances that, in some cases, go over the top of a mountain,” says Alison Brooks from George Washington University. > “There’s an occasional piece in the Acheulean that gets transported these distances,” says Brooks. “But we have thousands of pieces in this one site that’s smaller than most people’s kitchens. There has been a really major import of raw materials.”