Erik Rintamaki of Michigan is an avid rock collector. While searching for agates along Lake Michigan in 2017, he found stones that glowed under ultraviolet light. This is how he discovered a previously unknown mineral: yooperlight.

The name comes from the word “yooper” — someone who lives on the Upper Peninsula of Michigan. Rintamaki has trademarked that name. The scientific term is “cyenite clasts containing fluorescent sodalite.” These stones were brought to Michigan from Ontario by glaciers thousands of years ago. You can learn more about yooperlites in this video by Wonder World.


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