Who knew beaches in the dark could be so fun? Fluorescent rocks found on Michigan’s shores

Glowing rocks totally rock

Rocks before and after UV light (Michigan Rockhounds)

Leland, Mich. – What is dismissed in the daylight is considered treasure when the sun sets. While some hunt for the well-known, others know of a different prize that can only be found under the glow of a 365nm UV light.

On the shores of Van’s Beach in Leland, Michigan, people search the sand and the stones for the gold of the state of Michigan, the Leland Blue Stone. Born in the fires of the Leland Lake Superior Iron Company, Leland Blue has been around for over 100 years.

Leland Blues on a Beach (Michigan Rockhounds)

Michigan Rockhounds is an organization with a goal to educate Michiganders on Michigan’s geological history. Their team of content creators, geologists, and other staff built the Rockhounds community of over 60,000 people. With their research and guidance, we are able to deliver this glowing story to you.

According to the Michigan Rockhounds, the slag known as Leland Blue is the colorful byproduct of historical smelting operations. If like me, you have never heard of smelting before one sentence ago, Science Direct defines smelting as: “a form of extractive metallurgy to produce a metal from its ore. Smelting uses heat and a chemical reducing agent to decompose the ore, driving off other elements as gasses or slag and leaving just the metal behind.”

Michigan Rockhounds report that the sand and the stones that the Leland Blue hunters are sifting through also contain countless pieces of seemingly dull and boring slag glass. Pieces that most would not even recognize as slag if they were picked up. These weathered pieces of “historical garbage” are passed over in the search for the “more beautiful” Leland Blue. But in the dark, under UV light, they shine.

Sought-after Leland Blue in visible light (left) vs. under UV light (right) (Michigan Rockhounds)

Fluorescent sodalite, or Yooperlite, can be found on the shores of Leland. The dullest of dull Leland Blue shines the absolute brightest under UV light. While the most gorgeous sought-after pieces under daylight, look the dullest under UV light.

Not only can fluorescent slag be found under UV light, calcite will shine bright white, which allows fossils that might not even be noticed during the day, to become vibrant under UV at night.

Fossil before and after UV light (Michigan Rockhounds)

Phosphorescent calcite is also in abundance on these beaches. A big word I know, simply put, it means that the rock can hold onto energy from the light source even after the light source is taken away. Real-life glow-in-the-dark! If held under UV, this rock will continue to glow minutes after the light was taken away.

The source of the fluorescence in sodalite is disulfide, a variety of sulfur in the mineral, says Michigan Rockhounds.

This newly discovered treasure is covering the shores of Leland, and who knows, maybe the shores of other Michigan beaches that also have slag glass! So go get a UV light and plan an adventure in the dark to find these glowing rocks.

Check out more on the rocks from Michigan Rockhounds here.

Watch our interview with Cody from Michigan Rockhounds below:

What is dismissed in the daylight is considered treasure when the sun sets. While some hunt for the well-known, others know of a different prize that can only be found under the glow of a 365nm UV light.

About the Author:

Morgan is a senior at Wayne State University studying political science and communications.