Traverse City Record-Eagle

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July 1, 2013

Petoskey stones found throughout northern Mich.

TRAVERSE CITY — Part of the fun of being Up North is walking northern Michigan’s shorelines and back roads in search of Petoskey stones, the highly collectible pieces of hexagonal-patterned fossil coral that are prevalent in the area.

Along the way it’s possible to run into Don Reed. The South Boardman jewelry maker has sifted through gravel pits and strolled shorelines for years to collect Michigan’s native rocks and minerals, including Petoskey stones, that he uses to create his one-of-a-kind pieces.

Reed’s involvement with the Grand Traverse Area Rock and Mineral Club, his lapidary work — cutting and polishing stones — and his friendship with George W. Robinson, who holds a doctorate in geology and mineralogy and recently retired as the curator of the A.E. Seaman Mineral Museum at Michigan Technological University, piqued his curiosity about Michigan’s state stone, the Petoskey stone Hexagonaria percarinata, and the geological era in which it was formed.

Reed said Petoskey stones are pieces of Permian fossil coral formed about 350 million years ago during the Devonian Period of the Paleozoic Era when most of Michigan was under sea water. The stones can be found all over the world, but the finest stones are located in the northwest quadrant of lower Michigan in the rock strata known as Alpena Limestone that was churned into pebbles by Pleistocene glaciers about two million years ago.

“We know of nine different species of Petoskey stones. Their variations in color from almost white to light tan, dark gray or brown, help collectors differentiate them,” Reed said. “People pick up Petoskey stones and notice some have larger or smaller patterns and think they are baby rocks or adult rocks. They’re really different species.”

Reed particularly is interested in the extremely rare Petoskey stones with a pink coloration, and he and Robinson recently co-authored an article, “Pink Petoskey Stones from Northern Michigan” for the May-June edition of Rocks & Minerals magazine.

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