Lake Superior Agates
Hunt These Stunning Lake Superior Rocks!
If you're interested in treasure hunting, consider hunting for Lake Superior agates. In 1969 these Lake Superior rocks were designated by the Minnesota Legislature as the official state gemstone.
Our favorite Duluth Minnesota vacations always include some time to relax on the beach and hunt for agates. We choose a spot pretty much anywhere on the shoreline between Duluth and Grand Marais. We choose one of our favorite hotels in Duluth, and spend part of each day along the shore.
Agates found in Minnesota have a different color scheme than agates found in other parts of the world.
Their rich red, orange, and yellow coloring is caused by the oxidation of iron. The concentration of iron and the amount of oxidation determines the color within, or between, an agate's bands.
Agates are found in a variety of sizes from about the size of a pea to about the size of a bowling ball. Very large agates are extremely rare.
Small agates are often polished to make agate jewelry. Larger agates, called “lakers,” are sometimes cut into thin slabs that display the colored bands inside.
Moose Lake Agate and Geological Center: Located at the entrance to Moose Lake State Park, the 4,500 square foot building was opened in 2003 and includes a multi-purpose classroom, nature store gift shop, park offices, a resource workroom, restrooms, and an exhibition hall that showcases Minnesota's gemstone, the Lake Superior Agate. Interpretive displays focus on rocks, minerals and the geology of Minnesota.
The photo above is of just one of the many displays at the Moose Lake Agate Center.
Where Do We Hunt for Agates?
Every year our family spends a few days in a cabin on the North Shore of Lake Superior. The cabin is right on the shore of the great lake and the beach is cobbled with Lake Superior rocks.
Among the many activities that we want to do while we are there, agate hunting is high on the list.
When our kids were growing up they loved to just hunker down on the shore and sort through rocks looking for agates. Over time they became "experts" at recognizing the characteristics of agates. We bought a rock tumbler and spent many hours polishing up our finds after we got home.
I still have a huge plastic bucket in the basement full of small agates we found when the kids were young.
Types of Lake Superior Agates:
- Fortification Agate: most common type, colorful banding patterns that connect with like the walls of a fort.
- Parallel-banded, onyx-fortification or water-level agate: has straight, parallel bands over all or part of the stone.
- Moss agates: these have tree-branch-shaped bits of minerals embedded in them.
- Eye agate: desirable and rare Lake Superior agate, this stone has perfectly round bands or "eyes" on its the surface.
- Waterwashed agates: rare agates with smooth natural surfaces created from tumbling in the waves on a rocky beach.
- All-Timer Agates: a collector's dream agate, these agates weigh in at 2 pounds or more and have perfect shape, color, and banding qualities.
Agates are semi-precious gemstones that can be cut, polished and used in jewelry or, in the case of larger agates, for display. Not all agates found in Minnesota are of gemstone quality. The freezing and thawing to which they are subjected often causes fractures in the agates.
There are three techniques that can be used to cut and polish agates:
- Tumbling: this most common technique can be used with small agates. The stones are rotated in a rock tumbler with polishing grit to achieve a smooth and shiny surface.
- Diamond saw: used to cut medium size "laker" agates into slabs. The slabs can then be cut into artistic shapes--called cabochons--polished, and used in jewelry or artwork.
- Face polishing: involves polishing a curved surface on a part of the agate while leaving most of the agate in its natural state.
What Does an Agate Look Like?
The Lake Superior rocks we find on the beach won't look much like the ones we find in shops that sell agate jewelry and art items. So, how are you to know what to look for? If you want to be a serious agate hunter, I would suggest you buy a guide to Lake Superior agate hunting like one of those in the right column of this page.
Here are some basic clues to finding the Minnesota State Gem:
- The color band planes where an agate is chipped or broken are sometimes visible, giving the rock a "peeled" texture.
- Iron-oxide staining is found on nearly all agates and often covers much of the rock. The staining can most commonly will be shades of rust-red and yellow.
- Translucence is an optical feature produced by chalcedony quartz, the principal constituent of agates. The quartz allows light to penetrate, producing a glow. Sunny days are best for observing translucence.
- A glossy, waxy appearance, especially on a chipped or broken surface, is another clue.
- The surface of the rock is often pitted texture.
Other Place to Find Agates
The shores and beaches of Lake Superior are not the only places to find agates.
The Superior glacier lobe spread agates and other debris throughout northeastern and central Minnesota. Hikers, campers, hunters, and outdoor enthusiasts can readily collect them in many parts of the state...even right in the Twin Cities.
Here are some of the places where you can keep a sharp eye out for Minnesota agates:
- Along the Mississippi River and waters that empty into Lake Superior all along the North Shore.
- Along walking paths or trails in a wide swath from the North Shore to the Twin Cities.
- In the river rock that is used for landscaping around many business buildings.
- Farm fields in the spring or after a hard rain. Ask permission of course.
- Gravel pits and quarries if you can get permission to agate hunt in them.
- Virtually any place with exposed gravel and rocks offers the chance of finding Lake Superior agates...even if the location is far from the great lake.
Moose Lake Agate Festival
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