Michigan's State Stone

The Petoskey Stone

(Hexagonaria Percarinata)

 

 Is found throughout the northern lower penninsula and, in particular on the beaches. The most popular area to find wave washed pieces is on the beaches of the western side of our state, near the town of Petoskey which give the stone its name.

Petoskey stone is a fossilized coral of the Devonian period. It, and many other fossils are common in our state.

The appearance of Petoskey stone sometimes leads to it being described as having a "Turtleback" pattern. This causes some confusion because our state gem stone also has a "turtleback" appearance. In our gem stone the pattern is the result of chemical processes, in our state stone it results from the growth of the original coral.

The individual coralites or polyps (the animals which built the coral) formed "hexagonal" sections (that's where "Hexagonaria" comes from in it's scientific name) and Percarinata means "Very shell shaped" or "shaped like the keel (bottom) of a ship"
There are many species of Hexagonaria coral from around the world but Hexagonaria Percarinata is found only in the Michigan basin. 

 

For more information about Michigans state stone, try these links:

http://www.michigan.gov/documents/hal_mhc_mhm_petoskey_63854_7.pdf

http://www.michigan.gov/documents/deq/ogs-gimdl-GGPS_263213_7.pdf

http://www.michiganscience.org/15583

http://www.petoskeyarea.com/petoskey-stone-73/