From the glowing Yooperlites to Agates to Petoskey Stones, Michigan is a rock collectors heaven. Rock hunters from around the globe come to Michigan to find all the unique stones.

Yooperlites / Yooper Stones

Yooperlites were discovered in 2017 by Erik Rintamaki, who gave them their Michigan-themed name (Yooper as in UP or Upper Peninsula). Yooperlites are syenite rock rich with fluorescent sodalite. These rocks appear to be ordinary grey rocks until a UV light is shone upon them, when they glow a vibrant orange, red, yellow of pink.

Yooperlites have been found in different areas throughout Michigan but are most prominent in the UP along Lake Superior.

Things to Bring:

• UV Light: Get the best and brightest you can as you can’t find a Yooperlite without one. A filtered 365nm UV light is going to alert you to their glowing color the best. Avoid the cheap, small flashlight type lights as they make finding them very difficult.
• Headlamp/Flashlight: It gets dark out there! Make sure you have an extra light that can help you get back to your vehicle safely.
• Bag: A mesh bag works great when you’re in the sand and near the water.
• Rock Scooper: Not necessary but can be helpful, especially if you want to search in the Lake.

Pro Tips:

• Arrive at your location 15min before sunset. This give you a chance to get a location to search and familiarize yourself with the area. It won’t be dark enough to search until about 30min after sunset but getting there a little early helps you pick out a spot away from people.
• A great time to find rocks is in the spring when the ice has shifted and moved the rocks along the shore or after a storm when the waves have disrupted and uncovered new rocks.
• Searching along the water line may work great but most people know this and leave the rocks further up the beach unchecked so look there too.
• When searching larger rock piles point your light at an angle ahead you looking for an orange glow under the top layer of rocks. Most people search down and only see the very top layer of rocks and therefore heavily searched already.
• Buy the best, and strongest, 365nm UV light you can afford. Quality directly relates to the amount of glow you’ll see. Cheaper lights will make it very difficult to see.

Where to Look:

• Public Beach in Grand Marias (not the bay, Lake Superior side)
• Keweenaw Peninsula
• Whitefish Point Along Lake Superior

Petoskey Stone

The Petoskey stone is fossilized pre-historic coral, Hexagonaria percarinata. Distinguishable by its unique exoskeleton structure, a Petoskey stone consists of tightly packed, six-sided corallites, which are the skeletons of the once-living coral polyps. The center of each polyp was the mouth and contained tentacles that reached out for food. The hexagon shape of each cell and thin lines radiating out from the dark “eye” in the center are distinguishing features unique to this fossil.

Where to Look:

• Petoskey State Park
• Magnus City Park Beach
• Bayfront & Sunset Park

Lake Superior Agates

Agate is translucent to a semi-transparent form of chalcedony (quartz). If you have a piece that is semi-transparent you will be able to hold a very thin piece up and see distorted or foggy images through it. If you hold a translucent piece up to a source of light you will see a small amount of light passing through the thin edges.

The Lake Superior agate is noted for its rich red, orange, and yellow coloring. This color scheme is caused by the oxidation of iron. Iron leached from rocks provided the pigment that gives the gemstone its beautiful array of color. The concentration of iron and the amount of oxidation determine the color within or between an agate’s bands. There can also be white, grey, black, and tan strips of color as well.

Where to Look:

• Public Beach in Grand Marias (not the bay, Lake Superior side)
• Whitefish Point Along Lake Superior

Charlevoix Stone

The Charlevoix Stone is similar in appearance to the Petoskey stone, but has its own unique structure and features. A smaller exoskeleton allowed these coral colonies to live closer together to give the Charlevoix stone a distinctive honeycomb-like appearance. They’re slightly more rare than Petoskey stones, but it’s not uncommon to find both of these unique fossils while exploring northern beaches in Charlevoix or throughout northern Michigan.

Where to Look:

• Mt. McSauba Beach
• Lake Michigan Beach
• Beaver Island 
• Fisherman’s Island State Park
• North Point Nature Preserve

Chlorastrolite / Isle Royale Greenstones

Chlorastrolite occurs as amygdaloid structures and fracture fillings in basalt, and when the water and wave action has worn away the basalt, they are found as beach pebbles and granules in loose sediments. The Keweenaw nuggets are found as black to green colored nodules in vesicles of the amygdaloid basalts.

Where to Look:

• Shores of Isle Royale
• Keweenaw Peninsula

Jacobsville Sandstone / Redstone

Jacobsville Sandstone, or redstone, is generally red due to the presence of highly oxidized iron cement which binds together the grains of quartz. It’s typically mottled with various pinks, whites, and browns, exhibiting either many streaks or spherical spots caused by leaching and bleaching. It forms a wide belt through Northern and Upper Michigan and was quarried rather extensively at one time for use as building material to build the cities of Northern Michigan and elsewhere in the Great Lakes region.

Where to Look:

• Public Beach in Grand Marias (Lake Superior Side, not the bay)
• Au Sable Point, located around eight miles west of Grand Marais
• In general they can be found along most of the shores of the UP on Lake Superior