The Lake Superior agate is the state gemstone of Minnesota, prized for its rich coloring of red, yellow and orange, as well as for its distinctive "banded" patterning. This popular collector's rock can be found not only along the shores of Lake Superior, the largest of the Great Lakes and the largest freshwater lake on earth, but throughout much of the neighboring region.
Identifying Lake Superior Agates
A key to finding Lake Superior agates is the ability to identify them, which is not always easy. Some have the obvious banded patterning of an agate, or an iron-rich redness, but others look like plain brown or gray rocks, their beauty hidden inside. For this reason, it is important to use a field guide to minerals.
Lake Superior agates were distributed by the Superior Lobe Ice Age glacier approximately 10,000 years ago. They can be found anywhere along the path of the glacier, which includes most of the eastern two-thirds of Minnesota, northwestern Wisconsin and Michigan's Upper Peninsula.
All of the 2,700-mile Lake Superior shoreline is prime territory for lake Superior agate hunting. So are the waterways emptying into the Great Lake. Some rockhounds believe that the southern and western shores yield more agates.
Virtually any location in eastern Minnesota, western Wisconsin and northern Iowa where rocks are found in numbers can contain Lake Superior agates. They even can be found in large cities like Minneapolis.
Buying Lake Superior Agates
You can buy beautifully finished specimens of Lake Superior agates in rock shops, particularly those in the regions surrounding Lake Superior. Most of the towns along Minnesota's "North Shore," from Duluth to the Canadian border, have rock shops.