How to Polish Your Michigan Petoskey Stone
Advice from a rockhound
The beloved Petoskey stone. Nothing gets old about this 350-million-year-old fossil.
From Spring to Fall, millions of people come from all over the world to comb the shores of Northern Michigan in hopes of finding a Petoskey Stone. Memories are made during the hunt. Blue, cool, water licking ankles, toes touching sand, a breeze in your face … and then you see it … a rock looking back at you. Children and adults squeal with delight. There are high-fives all around.
But then, you get it home, intending to display your prized find and blink twice. Now it’s dry. What happened? Where did the eyes go? Is it sleeping or did it morph into a plain grey rock on the trip home? It looks nothing like the beauty you found in the water and far from the shiny, glass-like stunners you saw in the gift shops.
As an avid rockhound, I want to share my step-by-step guide to polish your treasures. It is a simple method, requiring sandpaper, time, and a lot of elbow grease. The reason Petoskey stones can be polished by hand is because they are relatively soft. On the Mohs scale of mineral hardness, from 1–10 a Petoskey scores a 3. To put it in perspective, talc scores a 1 and diamonds score a 10. This method won’t work with many other wonderful Michigan stones such as an agate…
