Minnesota’s state gem formed in gas bubbles in the same billion-year-old lava flows that made the Midcontinent Rift, then the glaciers tore them loose and spread them south across the whole state. The banded red-and-white ones take their colour from iron. Hunt the North Shore cobble beaches, and also the gravel pits and road cuts far inland, where the ice carried them. PUBLIC beaches allow reasonable hand collecting in many places, but NOT in state parks or national monuments; check the specific shore.
Agate (Lake Superior)
See it on the map
Other places on the map within a couple of hours.
