Beach Combing in Michigan

The eastern shore of Lake Michigan has miles and miles of sandy beaches and cliffs. It is very typical to see individual and families knee deep in 60 degree water searching for rocks. Some have special net bags to hold their treasures. Others use buckets. They are primarily searching for two types: Petoskey Stones and Leland Blues.

Petoskey Stones are fragments of a coral reef that was originally deposited during the Devonian period. When dry, the stone resembles ordinary limestone but when wet or polished using lapidary techniques, the distinctive mottled pattern of the six-sided coral fossils emerges. It is sometimes made into decorative objects. We saw jewelry, knives and kitchen utensils with stone handles, even tiles for a back splash. Other forms of fossilized coral are also found in the area.

Leland Blues are slag glass that was a waste byproduct from the iron ore smelting process used by the Leland Lake Superior Iron Company based in the town of Leland, Michigan. Beech and maple hardwood based charcoal with local limestone flux was used to refine the ore, with the slag consisting of iron ore impurities dumped into Lake Michigan. About 2% of the slag has the blue colour favoured by collectors. Leland blue slag glass is valued by collectors, jewelers, and lapidarists. It’s often used to make beautiful jewelry.

It is such a popular hobby Michigan law states that an individual cannot remove more than 25 pounds per year of any rock, mineral (exclusive of any gold bearing material) or invertebrate fossil from state-owned land for personal or non-commercial hobby use. It is illegal under federal law to remove stones from a National Lakeshore. Websites providing tips and locations abound such as the Michigan Rock Hounds site.