All 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.
This is just the newest area found to harbor hackmanite. Usually in any area where you find agates, there is also a strong possibility that hackmanite, or yooperlites, will also be present. They have also turned up in gravel pits in Minnesota, on Lake Michigan near the Chicago area and near the Point Betsie area near Frankfort, Michigan.
The tour groups go out at night and search for the rocks with UV lights and usually the “hunters” are successful. The largest one found to date weighs in about 5 pounds.
Few rules apply when searching for Yooperlites but always check local rules and restrictions. One that is often overlooked is remembering not to ever take anything from a national or state park. Many rock hounds are unaware of the little-known law in Michigan that it is illegal to take more than 25 pounds of rocks or minerals per year from any state park, recreation land or Great Lakes bottomlands. This is to ensure that all may share in some of Michigan’s resources.
Many folks flock to Whitefish Point in search of agates. It is illegal to search for rocks at Whitefish Point after dusk, the beaches are only open during twilight hours.
In light of this, it is still a good idea to get to the beaches where rock hunting is legal after nightfall while you still have some daylight so you can familiarize yourself with your surroundings. Be sure to have water, extra batteries and a place to stash your treasures once you find them.
You also need two lights, a white flashlight to scout the beach, and an ultraviolet light with which to illuminate the yooperlites. As with anything else, you can be as extravagant as you want. A $25 UV light will start you off just fine. Having a couple glow sticks are also helpful. Once you start walking the beach at night, it is sometimes hard to remember where you parked. Placing a glow stick where you walked down to the beach and a couple along the path you walk will help you find your way back.
From twilight through the night is the best time to find yooperlites. Go slow and don’t shine the light at right angles to the beach. Angling the light illuminates them better and don’t forget to retrace your steps as the light will illuminate the beach at a different angle. When you see a bright orange flash you know that you have found one.
Spring and fall are the best times to look. In spring everything gets “flipped” after the ice from the lake pushes everything around. It becomes a whole new area. Fall is also a good time because the winds of November also bring fresh rocks to shore. These two seasons also have less bugs and less tourists!
Although yooperlites are not new, they are a new discovery in the area. I like to look for the smooth gray and black rocks that the area offers up. They are great to paint and use in crafts. You can search for these, agates during the day, and yooperlites at night in this area. What could be better for rockhounds!