Country MoonAll rock hounds--take notice--there is a new kid on the block. Just last year a man in Michigan’s Upper Peninsula “discovered” what he named "Yooperlites."

Here’s the scoop: Erik Rintamaki has been a rock hound all of his life. He works the night shift at a casino and would often frequent beaches in the area after his shift. He was searching for rocks last summer when he found glowing rocks among the pebbles on a Lake Superior beach.

Michigan State University wanted to study them, so they, along with the University of Saskatchewan, researched them for months before Michigan State identified them as syenite clasts containing fluorescent sodalite. Fluorescent sodalite is known as hackmanite and has tenebrescence properties which simply means it has the ability to change color under various conditions. When viewed under ultraviolet light, it seems to glow, usually an orange or orange-red color. When the ultraviolet is removed, it fades back to its original color and vice versa. This works much in the same way as photochromic eyeglasses which darken when exposed to sunlight and lighten indoors.

Testing completed at Michigan Technological University confirmed that yooperlites contained sodium, alumina, silicon, chlorine and oxygen but not structural sulfur. Kevin Cole, professor of geology at Grand Valley State University in Grand Rapids, MI, accredits the fluorescent properties of these rocks to these ingredients.

Yooperlites have likely been in Michigan for centuries, left behind by the glaciers and rounded by the wave action of Lake Superior. So, technically, he did not discover them but he was the first person to get these rocks verified and has been credited with discovering this particular variation in Michigan which includes a Hackmanite-like fluorescent quality. The discovery was made public in May of 2018.

As with any new discovery, it peeks the interest of adventurers, especially rock hounds. Eric now gives yooperlite tours along the shores of Lake Superior in Luce and Chippewa counties and near Brimley. However, most of the specimens are found between Whitefish Point and Grand Marais on the Keewenaw Peninsula.

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