Petoskey stones and beach treasure: the collector's rules

The 25-pound rule is per person, per year, from state land and Great Lakes bottomlands. The magnificent ones stay.

The rule and the legend

You may take 25 pounds of rocks, minerals, and fossils per person per year from state-owned land and the Great Lakes shoreline. Generous for pockets, ruinous for boulders — as one Copemish man learned in 2015, when the DNR repossessed his 93-pound Petoskey stone. (It now greets visitors at the Outdoor Adventure Center in Detroit.) The limit covers the wet beach below the ordinary high-water mark, even in front of private cottages. That strip is public-trust land — the same zone the Glass v. Goeckel decision confirmed you may walk. The dry beach above it is the cottage owner’s; collect there only with permission. And the federal units — Sleeping Bear, Pictured Rocks, Isle Royale — allow no collecting at all. Admire, photograph, put it back.

The field guide

• Petoskey stones — fossilized coral (Hexagonaria), the state stone, 350 million years old. Best found wet in spring after ice-out along the northwest Lower Peninsula. Bring a squirt bottle — dry ones hide their pattern.
• Charlevoix stones — the Petoskey’s finer-patterned, rarer cousin. Same beaches, sharper eyes.
• Yooperlites — the great modern discovery (2017, by a Brimley rock hound): sodalite-bearing syenite that glows molten orange under 365nm UV light. Hunted at night on Lake Superior beaches near Grand Marais and the Keweenaw. The most fun $20 flashlight purchase in Michigan.
• Lake Superior agates, jasper, and float copper — Keweenaw beaches and gravels. A raw copper nugget connects you to 7,000 years of Michigan mining.
• Isle Royale greenstone (chlorastrolite) — the state gem and the heartbreaker: its namesake home is a national park where collecting is prohibited. Legal greenstones come from Keweenaw beaches and private claims.
• Leland Blue — beloved, beautiful, and technically not a stone. It’s Victorian iron-smelting slag from Leland’s foundry era — industrial history you can wear.
• Fossils at Rockport — Rockport State Recreation Area, a former limestone quarry on Lake Huron near Alpena, is the state’s designated fossil playground. Devonian corals, brachiopods, and crinoids, within the 25-pound rule.
• Beach glass — not a natural resource, so no limit at all. Enjoy.

The collector’s close

Polish a Petoskey with wet sandpaper through the grits and finish with polishing compound — or just keep a pocket stone worry-smooth. And when you find the giant one: photograph it, sit with it a minute, and leave it where the lake put it. That’s not just the law; around here it’s the manners.

The signpost

State-land rules at the DNR; the rockhound community’s guide at MichiganRockhounds.com. Start with the foraging pillar.