Lake Superior Agates were formed 1.2 billion years ago by volcanic activity. While the lava was cooling it would form gas pockets that would fill with mineral deposits like ferric iron, quartz or calcite as the years passed by. The quartz-rich deposits gradually crystallized into concentric bands (known as chalcedony) to form agates. Over time, like billions of years, the agates were freed from there rock by water and ice. Now, you’ll find them scattered all along the North Shore.
Lake Superior Agates are largely red, orange and (sometimes) yellow. Very different from other agates from around the world. The iconic red color is created by the oxidation of the iron in the rock. The color that appears between the bands is determined by the amount of oxidation that took place when the rock was formed.
Agates can range significantly in size with the vast majority of them being small, pea-sized or smaller stones. However, some weigh over 20 pounds — they’re about the size of a bowling ball! While there are multiple types of Lake Superior Agates the most common are fortification agates with the classic bands.
How to Find Agates:
Look for these clues when you’re on the hunt:
- Stones that appear shinier and more translucent than others around it
- Stones with colored bands
- Rust-red or yellow stained rock surfaces (caused by iron oxide)
- A surface that has a pitted texture
- It is often helpful to dig down a little
Where to Look
Agates can be found almost anywhere there is exposed rock or gravel. Sometimes they can even be found on the road. Lake Superior beaches along Highway 61 that we recommend for agate hunting include:
- Brighton Beach, Duluth
- Burlington Bay, Two Harbors
- Flood Bay Wayside (1 mile east of Two Harbors)
- Cut Face Creek Wayside Rest (14 miles north of Lutsen)
- The mouth of Devil Track River (3.7 miles east of Grand Marais)
- Five Mile Rock Beach (5 miles east of Grand Marais)
- The mouth of the Kadunce River (12.7 miles east of Grand Marais)
- Paradise Beach (13 miles east of Grand Marais)
- Brule River (14.5 miles east of Grand Marais)
- Horseshoe Bay (24 miles east of Grand Marais)
Back in 1969, the Lake Superior Agate beat out other types of rocks like Binghamite yellow silkstone, Thomsonite, and pipestone to become Minnesota’s state rock.
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