%0 Journal Article %J American Anthropologist %D 1904 %T Aboriginal Trephining in Bolivia %A Bandelier, Adolph F. %P 440-446 %V 6 %Z obsidian called chillisaa kala or "black flint", while "llisa" means "white flint". Obsidian, where available, was probably used trephining (p446). Also quotes Cobo on stomach operations using obsidian.