Lake Superior Agates
Lake Superior agates are a treasure to find. These unique stones were created by volcanic activity along the North Shore 1.2 billion years ago when gas pockets in the molten lava filled with mineral deposits, like ferric iron, quartz, or calcite. Then, the pockets that were filled with quartz-rich deposits gradually crystallized into concentric bands, known as chalcedony, to form agates. Over time (like, a billion years, give or take) the agates were freed by water and ice from the lava rocks and deposited along the North Shore.
You can find red, orange, and sometimes yellow Lake Superior Agates. These are very different from other types of agates found throughout the world. This is due to the oxidation of iron, which creates the beautiful red colored bands in between the other rock layers. The color is determined by the amount of oxidation that took place when the rock formed, so each agate is a little different from the next.
The size of the agates on the North Shore also varies considerably. You can find tiny pea-sized agates and, if you’re very lucky, you can find agates that weigh upward of 20 lbs and are the size of a bowling ball!
Agates were actually named the Minnesota state rock in 1969, and agate hunting is a popular past time on the North Shore and a great activity for the entire family. Here are some tips and clues on how to find the best North Shore agates:
- Stones that appear shinier and more translucent than others around it (look for the sparkle on a sunny day or glistening rocks on a rainy day)
- Stones with colored bands
- Rust-red or yellow stained rock surfaces (caused by iron oxide)
- Surfaces that have a pitted texture
Best Beaches For Agates:
- Brighton Beach, Duluth
- Burlington Bay, Two Harbors
- Flood Bay Wayside, Two Harbors
- Cut Face Creek Wayside Rest, between Lutsen and Grand Marais
- Devil Track River (mouth), Grand Marais
- Five Mile Rock Beach, Grand Marais
- Kadunce River (mouth), Grand Marais
- Paradise Beach, Covill
- Brule River, Hovland
- Horseshoe Bay, Hovland