Everyone from the casual rockhound to Michigan-born Grammy winner Billy Strings is obsessed with finding these glowing rocks.

Hint: You're going to want a UV light for this.

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What Are Yooperlites?

Also called "Glowdalites" -- certainly not by anyone around here -- the word Yooperlite is a play on Michigan's Upper Peninsula a.k.a. "The U.P." we trolls who live under the Mackinac Bridge refer to residents of the U.P. as "Yoopers".

Mackinac Bridge
Mackinac Bridge - Canva

However, "Yooperlite" is actually a misnomer. While fluorescent sodalite syenite is most commonly found in Michigan's Upper Peninsula it can also be found scattered throughout the Great Lakes-- and the world! It can even be found further inland.

According Michigan Rockhounds these "incredibly plain-looking" looking rocks were formed 1.1 billion years ago,

 ...during a spectacularly violent geologic period when North America attempted to tear itself in two...near the modern shore of Lake Superior, another large body of magma was trying to reach the surface. That magma never quite made it all the way up to form another volcano. Instead, that magma hardened beneath the ground to form a type of granite called “syenite” and this one had a lot of a mineral called “sodalite.”

Yooperlites - World Wonder via YouTube

How To Find Them

Brought to Michigan by glaciers during the last ice age these glowing rocks are nearly impossible to spot by the naked eye. As with most hobbies the more money you invest on quality gear the more success you'll have.

Michigan Rockhounds recommends avoiding the cheap 395 nm flashlights as they're "simply terrible". I used this site as a guide when purchasing my UV light off of Amazon and opted for a modestly-priced 365 nm flashlight instead.

I'm heading up to the Petoskey area soon and I'm hoping that's far enough north to find both Petoskey stones and Yooperlites. When searching for these rocks in particular the Rob Wolfe with the Michigan EGLE recommends:

  • Starting with a beach that has known stones and allows rockhounding
  • "Go early in the season when cooler temperatures keep most people off the shoreline"
  • "It is best to go immediately after a storm as new material is washed up, but not during the storm"
  • "Look not only along the shoreline but out into the water (as far as the light can reach)"
  • "Walk at a normal pace and shine the light with a sweeping motion"

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