What’s a Petoskey Stone?
The Petoskey Stone is a coral that lived 350 million years ago during the Devonian age when the northern part of Michigan was covered with a sea of warm water. The scientific name is Hexagonaria percarinata (Hexagonaria meaning having six sides).
The soft living tissue of the corallite was called polyp. At the center of the polyp was the food intake opening or mouth. This dark spot, or the eye of the corallite, has been filled with silt or mud that petrified after falling into the openings. Surrounding the opening were tentacles that were used for gathering food and drawing the food into the mouth. This living corallite thrived on plankton which lived in the warm sea.
Calcite, silica and other minerals have replaced the original elements in each cell. Each chamber or corallite at one time was a living marine animal that grew in colonies. The Petoskey stone is also known as a colony coral.
Where can the Petoskey Stone be found?
The Petoskey stone can be found in Michigan from the shores of Traverse City across the state to Alpena. It can be found in gravel pits, on road beds, and mainly on the shores of Lake Michigan around the Petoskey area.
Early spring is a good time to look for the stone after the ice has melted along the shore. Each year as the ice of Lake Michigan breaks up and the wind shifts the ice back and forth, it pushes a new crop of fossils to shore. During the summer months the best time to look for the stone is after a wind storm or during a mist rain when the stones will show the fossil pattern more clearly.
Why Petoskey Stone?
The city of Petoskey was named after an Ottawa Indian Chief, Chief Pet-O-Sega. "Pet-O-Sega" means the "Rays of the Rising Sun". The eye of the stone is seen as the sun, and the lines or tentacles are seen as the rays radiating from the sun.
The stone was named Petoskey because of the abundance of them found on the shores of Little Traverse Bay. In 1965 the State of Michigan adopted the Petoskey stone as Michigan's state stone.
How to identify a Petoskey Stone.
Keeping in mind the scientific name, Hexagonaria, helps when looking for the stone. Its six sided pattern will allow you to identify it from other fossils. The pattern of the Petoskey stone fossil can be as little as 1/6 of an inch or larger. There are different grades of the stone from a porous soft stone to a very unique harder one. The stone can be found in many different variations from a whole Petoskey specimen to only a portion of the stone being "Petoskey". Being a fossil it is naturally soft and can have many imperfections such as cracks and other mineral deposits mixed in.
A Petoskey stone found on the beach can be smooth, and the fossil can be very distinct. This is not only because of the wave action of the water, but because the stones have been tumbled and rolled against other stones and smoothed by the sand. The pitted, rougher stones are usually found on shore or inland.
Puzzles That Rock
Keep the memories of Petoskey Stone hunting alive with this fun jigsaw puzzle! Anyone who has ever walked the beaches in search of Michigan's state stone will appreciate the picture. "Rising Sun - A Petoskey Stone Puzzle" is available in stores in Petoskey's Gaslight District and is also offered online. New Petoskey Stone puzzles are added occasionally, too.