Treasure hunting: Find the Lake Superior agate

Lake Superior agates

Examples of Lake Superior agates. Photo by Kate Perkins

Spring is the perfect time to search for the Lake Superior agate, the beautiful banded rock that’s the Minnesota state gemstone.

While different kinds of agates are found all over the world, Lake Superior agates are marked by their red and white stripes. According to the DNR, Lake Superior agates began forming more than a billion years ago, when North America began to split in two. Right at the tear, which is now the Lake Superior region, lava rich in iron flowed to the surface of the earth. The lava had gas bubbles within it, which cooled to form what are called vesicles in the rock. Later, groundwater that was rich in quartz and other minerals flowed into the vesicles. When it flowed out, it left some of those minerals behind, forming the concentric lines of color characteristic of agates. In Lake Superior agates, many of those layers are red due to the presence of iron in the groundwater. The type of fine-grained quartz that makes up an agate is called chalcedony.

Around two million years ago, agates were freed from their host rock, the hardened lava that had flowed from the earth. An ice age overtook the earth, and huge glaciers moved over the lava, not only freeing the agates but carrying them south and west, over the Whitefish Chain and many other areas of the state.

 

Agates range in size from small pebbles to larger than softballs. Large agates are rare, though, and usually agates found in the Whitefish area are around the size of a quarter, or smaller. Usually they’re red and white striped, but they can also have stripes that are orange, yellow or pink, and even rarely blue. Agate collecting is a great activity for all ages. Finding an agate can make a lasting memory, and the rocks are great to take home as souvenirs or additions to your rock collection.

Even though their name suggests that they’d only be found at Lake Superior, Lake Superior agates are found across the state and even as far south as Iowa. They’re commonly found in the area around the Whitefish Chain.

Where to look for agates:

Lake shores are a great place to look for agates, especially in the spring. The shore changes over the winter, especially during ice out. This can move fresh rocks onto the shore that others haven’t looked through.

Dirt roads are also a great place to search for agates. Walking in the sunshine and looking for agates is, for many, a favorite afternoon pastime. Often the dirt and rocks dumped onto dirt roads for maintenance can be full of Lake Superior agates.

Tips for spotting agates:

When searching for agates, look for the characteristic red and white banding. Sometimes, though, one side of an agate will appear all red or all white, but flip it over and you’ll see a wide array of colors. Another great way to search for agates is to look for their glassy, waxy texture.

Sunny days are great for agate hunting. Because agates tend to be translucent, they’ll sometime shine in the sunlight with a red glow. If you’re unsure whether or not you’ve found an agate, try getting the agate wet. Water can bring out an agate’s stripes, making it easier to identify.

Finding agates can take a little practice, but once you know what to look for, it’s a rewarding hobby!

For more information on finding agates, take a look at these online and print resources:

]“Agate Hunting Made Easy,” by Jim Magnuson

“Central Minnesota a prime spot for agate hunting,” article in the St. Cloud Times

Agate Lady’s agate basics

 

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