Prehistoric stone tool quarries can be a source information about past resource exploitation and management, tool production, and labor organization. Research is complicated, however, by the sheer abundance of discarded material and by a dearth of temporally diagnostic evidence. Here we discuss research at stone sources in light of ongoing work at the source of Quispisisa Type obsidian in highland Peru, where exploitation resulted in the excavation of numerous quarry pits and the accumulation of tailings piles and knapping debris. Using this lithic resource as an example, we discuss approaches to stone tool sources, including system-oriented and regional-scale investigations as well as considerations of the social and ritual significance of geological source areas.