Where is Petoskey Stone found?
Fossilized Hexagonaria percarinata
Got a photo? Identify rocks instantly with the Rockby app
Open the appPetoskey Stone occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Petoskey Stone
Michigan, USA
Predominantly found in the Traverse Group formations of the northern Lower Peninsula of Michigan, particularly along the shores of Lake Michigan and Lake Huron, and in riverbeds and gravel pits. Notable locations include Petoskey, Charlevoix, and other areas around Little Traverse Bay.
Indiana, USA
Less common, but similar Devonian coral fossils can be found in parts of Indiana.
Iowa, USA
Some Devonian coral occurrences are noted in Iowa, though Hexagonaria percarinata specifically is less prevalent than in Michigan.
Collecting tips
- Search in Water. The distinctive pattern of Petoskey Stones is much more visible when the stone is wet. Search along shorelines, especially after storms, or in shallow water.
- Look for Hexagonal Patterns. Identify the characteristic honeycomb-like hexagonal patterns on the surface of the stones. Each hexagon should have a small 'eye' or dot in the center.
- Check Hardness. While the original coral was calcium carbonate (Mohs 3), the silicified fossil is much harder (Mohs 6.5-7), similar to quartz. This can help differentiate it from non-silicified coral fossils.
- Visit Known Locations. Focus your search on well-known areas in Michigan, such as the beaches around Petoskey and Charlevoix, where they are abundant.
Quick Check
- Color:
- Gray to tan with darker hexagonal patterns.
- Luster:
- Dull to earthy (unpolished), vitreous to waxy (polished).
- Streak:
- White (due to the quartz composition).
Explore Petoskey Stone
Identify rocks anywhere
Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.