Near Grand Meadow in southeastern Minnesota, an Indigenous open-pit quarry known as Wanhi Yukan, “There Is Chert Here,” supplied chert used for toolmaking for thousands of years. The stone, formed about 385 million years ago and lying close to the surface, could be worked predictably and became especially important between about 950 and 1400 CE, when intensive digging created the most extensively used Native American toolstone source known in Minnesota. Evidence of pits, ramps, hammerstones, and flintknapping debris shows extraction and partial shaping on site. Artifacts of Grand Meadow Chert found across Minnesota and neighboring states reveal wide networks of movement, exchange, and cultural connection.