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What is a Petoskey Stone?
Around 350 to 400 million years ago the land we know as Michigan was located near the equator. Covered by a warm, shallow, saltwater sea, the colonial coral Hexagonaria Percarinata thrived with other marine life in tropical reefs. The earth’s plates moved and pushed Michigan north to the 45th parallel and above sea level, which created dry land formations.
More recently, about two million years ago, glacial action scraped the earth and spread the fossils across the northern Lower Peninsula, depositing major concentrations in the Petoskey area. The prehistoric fossil, unique to the Traverse Group rock strata, is called the Petoskey Stone and is Michigan’s official state stone.
A Petoskey Stone consists of tightly packed, six-sided corallites, which are the skeletons of the once-living cor-al polyps. The dark center (or eyes) were the mouth of the coral. The lines surrounding the eyes were once tentacles which brought food into the mouth. The Petoskey Stone, like the city, was named for the Ottawa Chief Pe-to-se-ga (Rising Sun) because the stones pattern looks like the rays of the sun. When dry, the stone resembles ordinary limestone but when wet or polished using lapidary techniques, the distinctive mottled pattern of the six-sided coral fossils emerges.
Then and NowOf course we can't know for sure what the colonial coral Hexagonaria Percarinata looked like, but many believe this is how it would have appeared 350-400 Millions Years Ago.
Many Shapes and SizesYou will find Petoskey stones in many shapes and sizes. No two really are the same!
Hot Spots!Petoskey State Park:
With two miles of shoreline on Little Traverse Bay (and Lake Michigan), this is a natural for novices as well as experienced rockhounds. Located on 303 acres between Petoskey and Harbor Springs off Hwy. M-119. Recreation passport required for entry.
Magnus City Park Beach:
Easy access to the waterfront and Petoskey Stone hunting at this park with 1,000 feet of beach.
Bay Front & Sunset Park:
Walking distance from Downtown near the marina.
Polish it Up!Polishing the Petoskey Stone at home is easily accomplished by using sand paper! Begin with a relatively coarse grade of sand paper, graduating to finer grades. Smooth out sanding marks with very fine steel wool, or wet/dry sand paper and finish with leather or cloth soaked in oil. Do not use a rock tumbler, as the Petoskey stone is too soft and will be damaged.
Find A Petoskey Stone Retailer
Not a Rockhound? Staying in the winter months? Find your perfect Petoskey Stone at one of our fantastic retailers.
Insider Information Alert!Learn more about our State stone, and some of the best local places to find your own Northern Michigan treasure!
How and Where to Find
The most popular place for hunting Petoskey Stones is a Lake Michigan beach. Although the beaches are the hot spots, those ancient glaciers spread the fossils around the area and rockhounds know to leave the lakeshore to search cut roadbeds, gravel pits and even farmer’s fields.
Dry Petoskey Stones usually look like ordinary limestone in a color range from light grey to dark grey. The distinctive, six-sided “rays of the rising sun” pattern pops when the rock’s surface is wet, which is why it’s easier to spy Petoskey Stones along the shore or by wading out into the water. If you’re hunting in a dry area carry a water bottle to spray likely candidates to bring out that pattern.