(WWJ) Sparkling "Yooperlites" are capturing the attention of Upper Peninsula residents, visitors, and the curious online...but what the heck are they?

Posted on the "Yooperlites" Facebook page are stunning photos of glowing Syenite rocks, spotted using a specialized flashlight along Michigan's Lake Superior shoreline.

Video of Yooperlites !! Picking Yooperlites on Lake Superior

"These things are a blast to find," Superior Township resident Erik Rintamaki told WWJNewsradio.com.

He offers guided walking tours to search for the special rocks, which glow when exposed to UV light due to the presence of the fluorescent mineral Sodalite.

"I've been a rock picker all my life. I got it from my dad, who got it from his dad," said the 43-year-old, who has a side business as an agate dealer.

After getting a hold of the right type of light, Rintamaki first found a Yooperlite one night last year. "I was just screaming on the beach I was so happy," Rintamaki said, although he had no idea what he was holding -- even after doing some Googling and asking around.

"I took them to all the rock and mineral shows and no one could identify them," he said, "...so I nicknamed them "Yooperlites."

It may seem like a funny name; but as Rintamaki points out, Michigan's beloved Petoskey stone is in fact hexagonal coral, though hardly anyone calls it that.

While he wasn't the first person to discover the mineral itself, Rintamaki is credited with bringing it to Michigan Tech University geologists who were able to verify for the first time that there is Sodalite in Michigan; perhaps brought down from Canada by glaciers.

Rintamaki ended up being published in the Mineral News for the discovery, and his tours are really taking off.

"I'm completely sold out for 2018 and I'm already booking for next year," Rintamaki said. "It's $50 a person; you get a light you get to keep and you get to keep all the stones you find."

If you want to try searching for yourself, Rintamaki​ said "Yooperlites" can be found mostly along Lake Superior between Whitefish Point and Grand Marais, Michigan, and on the Keweenaw Peninsula.