4.7" Polished Banded Lake Superior Agate - Minnesota

Lake Superior agate is a variety of agate that's collected throughout Minnesota. It commonly features red, orange, yellow and white concentric banding, the red, orange and yellow of which can be attributed to iron impurities. This makes sense considering iron is a major industrial mineral that's found throughout the Cuyuna, Mesabi, Vermillion and Gunflint Iron Ranges that make up much of the northeastern region of Minnesota, along one side of Lake Superior. They formed by silica/iron-rich fluid deposition within vesicular pockets which were created by gasses within lava rock as it cooled. Over time, the agate nodules eroded out of the rock and were naturally dispersed by glacial activity throughout multiple regions of Minnesota, Iowa, Kansas, Michigan, Nebraska and Wisconsin. It is such a prominent mineral with a rich and insightful history, that it was designated as the official state gemstone of Minnesota.