Michigan officials want to talk to man who found ‘unusual’ stone

Robert Allen, | Detroit Free Press

DETROIT — Three days after a man hauled a 93-pound fossilized coral stone out of Lake Michigan, state officials are still looking to speak with him.

Michigan law prohibits removing more than 25 pounds of rocks or minerals per year from state-owned lands, including Great Lakes bottomlands. Violation could bring a civil fine of up to $500. The Associated Press reported Thursday that the Michigan Department of Natural Resources wants to talk with Tim O'Brien, who found the rock, to decide how to handle the matter.

"We just want to talk to him, because we haven't been able to have a conversation with him," the DNR’s Ed Golder said Friday afternoon.

The Petoskey stone, "a fairly unusual find," appears to be an interesting-enough specimen to have a place at the Michigan Historical Center in Lansing, Golder said.

O'Brien of Copermish, south of Traverse City, didn't immediately respond to a request for comment with the Free Press. The Grand Rapids Press previously reported that he found the Petoskey stone near Northport and lugged it to shore Tuesday.

So what is a Petoskey stone?

Petoskey, Michigan's state stone, is fossilized coral that lived in the warm, shallow seas covering Michigan during the Devonian era about 350 million years ago. At the time, the area was near the equator and covered by warm, shallow seas, according to an article from the Michigan Department of Environmental Quality, Geological Survey Division.

The Petoskey stone genera of corals are found in Iowa, Indiana, Illinois, Ohio, New York, Canada, Germany, England and Asia. About 2 million years ago, Pleistocene glaciers plucked Petoskey stones from the bedrock and spread them across Michigan and surrounding areas, according to the article.

"This is why Petoskeys can be found in gravel pits and along our beautiful beaches far from the Petoskey area," according to the article.

Petoskeys are a nice specimen for polishing because they're mostly calcite, which is soft enough to be easily worked yet dense enough to take a nice polish. Many that can be found in Michigan have been rounded by running water from the glaciers or waves on the beach, the article reports.