Saint Mary Parish

Historical marker location:

157 High Street, Williamston, Michigan

( Marker is at the intersection of High Street and North Cedar Street, on the right on High Street.)

Marker installed: 1994

Michigan is the only state to have two designated "state stones": the Petoskey Stone, which is the state stone of Michigan, and the Isle Royale Greenstone, which is the state gemstone of Michigan. The Petoskey Stone is a fossilized coral that is found primarily in the northern Lower Peninsula, while the Isle Royale Greenstone is a rare mineral found only on Isle Royale in Lake Superior.