(Internal # F830-104) This is a medium, genuine Petoskey fossil coral stone, polished specimen, average 1-3/4 to 2" long. ?They are fully (professionally) polished on one side, lightly polished on the other side?. Petoskey stones are a gray color. What you see in to photo is what you get. PETOSKEY STONES THE ROCK THAT'S ACTUALLY A FOSSIL! (Fossil coral, Hexagonaria percarinata) This is fossil coral, with a beautiful honeycomb pattern, fairly soft at Mohs 3 on the hardness scale. Michigan's State Rock. Antrim County MI holds a Petoskey Festival each year. Formed when Michigan was covered by a sea in which coral reefs thrived, the coral gradually became buried by sediment, which turned into limestone and shale. The skeletons were replaced by calcite (calcium, carbon oxygen). During the Ice Ages, from 1.6 million to 10,000 years ago, glaciers scraping over Michigan broke up soft, fossil-bearing rocks. The pieces were carried along and dropped, now found along lake beaches, road cuts, and gravel pits as rounded stones from pebble size to potato-sized lumps. Dated to 350 million years old (Devonian period). Found on the shores of Little Traverse Bay from the northwestern tip of the Lower Peninsula, especially around Petoskey and Charlevoix, Michigan. The name "Petoskey" comes from an Ottawa Indian chief. When he was born, sunbeams fell upon his face so he was named Pe-tos-e-gay ("rising sun"). European settlers Anglicized the name as Petoskey. WE SHIP WORLDWIDE, see the chart for postage to your country. Click on our Store tag for SIMILAR items. PETOSKEY STONES ARE A GRAY COLOR.