What Is A Petoskey Stone? Facts, Legend, & Polishing

A Petoskey Stone is a combination of a rock and a fossil which was living during the Devonian period. After this period, the glacial ice would loosen stones from the bedrock and having ground off their edges and polished them, deposit them on what is now the Northwestern portion of Michigan’s Lower Peninsula.


unpolished petoskey stone


Although when these stones are dry, they resemble regular limestone, when they are wet or polished they display a pattern which reveals six-sided coral fossils. In the area as the Petoskey Stones are found, other fossilized corals have been found including some with complete coral colony heads which had been fossilized. The stones are often polished to make uniquely decorated objects such as Petoskey Stone jewelry.

The Name

In 1965 the Petoskey stone became the State Stone of Michigan where there is also a town with the same name. Michigan is the only known place where Petoskey stones can be found, and there is a local legend behind the name Petoskey which makes the stones uniquely Michigan.

The Legend 

The name Petoskey is a corruption of the Indian name Pet-O-Sega, which can mean “Sunbeams of Promise,” “Rising Sun” or “Rays of Dawn” and was the name of an Ottawa Indian Chief. Legend has it that this great Indian chief was the son of a fur trader who was the descendant of French nobility and the daughter of an Indian chief, therefore a Princess. The name was given to him as rays from the sun fell on his face as he was born and his life certainly showed that those rays were indeed rays of promise.

He became a wealthy fur trader and was able to buy a great deal of land for himself and his tribe. He married another Ottawa Indian woman, and between them, they had two daughters and eight sons. In 1873, several years before the chief’s death, a city had begun to emerge on his lands and in reverence to the chief; the city was named Petoskey, an Anglicized version of the Indian name.


polished petoskey stone

For Petoskey stones to display their unique look and thereby become beautiful ornamental pieces, it is necessary to polish them with the lapidary techniques which involve cutting and grinding as well as polishing. The people that do this are called lapidarist and although they cutters of many gemstones, they are often mistaken for diamond cutters but they are not. Although similar techniques are used by a gem cutter and a diamond cutter, due to the qualities of a diamond extra skills and tools are needed to those of a regular gem cutter or lapidarist. This means that although the stones may fairly easily be found, for them to become beautiful, unique ornamental pieces, a cost is involved for their polishing.

How To Polish A Petoskey Stone

You can find polished Petoskey stones in gift shops throughout Northern Michigan but what if you'd like to make these rocks shine yourself? Luckily, you can do this right at home with a few supplies and some elbow grease. 

Rock Polishing Supplies You Need

  • Petoskey stone - sort through your Petoskey stone collection to find the one (or ones) you want to transform into a shining gem.
  • A file - although this tool isn't required, it helps get rid of uneven areas and creates a smoother shape.
  • 220 grit sandpaper - This rough sandpaper can be found at any hardware store.
  • 400 grit sandpaper - Used to remove scratches from the coarser 220 grit.
  • 600 grit sandpaper - For that final sanding that gets rid of fine scratches.
  • Polishing compound - You can use one specifically for rock polishing but car-finish rubbing compound works great too!
  • Velvet fabric - This soft fabric works great for rubbing the compound into the stone and creates that shine you're looking for. You can also use a piece of denim cloth!
  • Towel & water - To rinse and dry of course!

Steps To Polish Your Petoskey Stone

  1. Choose your favorite Petoskey stone to polish.
  2. Use your file to remove small bumps and rough edges. Don't worry about scratches.
  3. Dampen your stone with water and sand in a steady, circular motion using the 220 grit paper.
  4. Rinse the stone and lay it on the towel. Examine the stone for scratch marks.
  5. Repeat the sanding process using 400 grit paper. Rinse, dry, and examine your stone.
  6. Use the 600 grit paper for the final sanding process. This is the finest paper and will remove the last scratches to create a smooth surface. Sand for 5 to 10 minutes.
  7. Rinse and dry your stone.
  8. Apply a quarter-size amount of polishing compound to your stone.
  9. Using the polishing cloth, apply pressure in short, circular motions while working from the top to the bottom.
  10. Inspect your stone to make sure all scratches are removed and you are happy with the shiny surface.
  11. Wipe off your stone with a clean cloth and you are good to go!


Petoskey stones are a popular choice for creating handmade Michigan jewelry, such as necklaces.

A Petoskey stone is, therefore, a fossil, a stone, a gem which was created thousands of years ago but can become a unique ornament with more modern techniques.


Image credits:

The Children's Museum of Indianapolis [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)]

David J. Fred (Dfred) [CC BY 3.0 (https://creativecommons.org/licenses/by/3.0)], from Wikimedia Commons

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