What’s Petoskey stone, and The place Can You Discover It?

Petoskey stone is a rock and a fossil, typically pebble-formed, that’s composed of a fossilized rugose coral, Hexagonaria percarinata.

Why is it referred to as the Petoskey Stone?

The identify Petoskey Stone possible happened as a result of it was discovered and bought as a memento from the Petoskey space. The identify Petoskey seems to have originated late within the 18th century. Its roots stem from an Ottawa Indian legend.  In 1965, Petoskey stone was named the state stone of Michigan.

How was the Petoskey stone shaped?

So, what’s a Petoskey stone? It’s a fossil colonial coral that lived within the heat Michigan seas through the Devonian time round 350 million years in the past. The identify Hexagonaria (which means six sides) percarinata was designated by Dr. Edwin Stumm in 1969 due to his in depth information of fossils. Any such fossil is discovered solely within the rock strata referred to as the Gravel Level Formation. This formation is a part of the Traverse Group of the Devonian Age.

The stones have been shaped because of glaciation, through which sheets of ice plucked stones from the bedrock, grinding off their tough edges and depositing them within the northwestern (and a few within the northeastern) portion of Michigan’s decrease peninsula. In those self same areas of Michigan, full fossilized coral colony heads may be discovered within the supply rocks for the Petoskey stones.

POLISHED  Petoskey stone

In the course of the Devonian time, Michigan was fairly totally different. Geographically, what’s now Michigan was close to the equator. A heat shallow sea coated the State. This heat, sunny sea was a really perfect habitat for marine life. A Devonian reef had sheltered clams, cephalopods, corals, crinoids, trilobites, fish, and lots of different life types.

The mushy dwelling tissue of the coral was referred to as a polyp. On the middle of this was the world the place meals was taken in, or the mouth. This darkish spot, or eye, has been full of mud of silt that petrified after falling into the openings. Surrounding the openings have been tentacles that have been used for gathering meals and drawing it into the mouth. The dwelling coral that become the Petoskey stone thrived on plankton that lived within the heat sea.

Calcite, silica and different minerals have changed the primary parts of every cell. Every separate chamber, then, on every Petoskey stone, was a member of a thriving colony of dwelling corals. For that purpose the Petoskey stone is known as a colony coral.

The place can you discover the Petoskey stone?

Underwater rocks in Lake Michigan

Petoskey stones may be discovered on numerous seashores and inland places in Michigan, with most of the hottest being these surrounding Petoskey and Charlevoix. The motion of the frozen lake ice appearing on the shore through the winters is assumed to show over stones on the shore of Lake Michigan, exposing new Petoskey stones on the water’s edge every spring.Petoskey Stones are additionally generally present in Iowa, Indiana, Illinois, Ohio, New York, Canada, Germany, England, and even Asia.

Pleistocene glaciers (about two million years in the past) plucked Petoskey stones from the bedrock and unfold them over Michigan and surrounding areas. For this reason Petoskey stones could be present in gravel pits and alongside seashores removed from the Petoskey space.

The most effective time to seek out the Petoskey stones is early spring after the ice on Grand Traverse Bay has melted alongside the shore. Annually because the ice is damaged up and the winds push the ice in several instructions, it pushes a brand new crop of Petoskey stones in the direction of the shores.

The way to Polish Petoskey Stones by Hand

Petoskey stones are made up of calcite, and subsequently are a great candidate for hand sprucing. Calcite is delicate sufficient in order that it may be simply labored, however dense sufficient to take a pleasant polish.


  • Petoskey stone
  • Sandpaper (220, four hundred, or 600 grit)
  • A thick towel or newspaper
  • A bit of corduroy or velvet
  • Sprucing powder
  • Water

Upon getting discovered the stone you need to polish, sand it down with the 220 the sandpaper talked about above. After rubbing, rinse the stone down and dry it off. Look at the stone for scratch marks, and if there are any, carry on sanding! All scratch marks ought to be gone!  Subsequent, sand once more with four hundred grit sandpaper. This could take away any coarse spots. As soon as once more, rinse, dry and examine.  Now sand the paper with the 600 grit to be sure that the stone is clean and scratch free. Once you assume it seems to be good, proceed sanding for an additional 10 minutes, simply to ensure.  At this level, it’s time to polish. Sprinkle the damp corduroy or velvet with sprucing powder. A brief, rotating rubbing will polish the stone. Nevertheless, if scratches seem, begin from the start with the 220 grit paper to take away them!  Once you’re completed with the sprucing, merely rinse the stone off in clear water, and dry. Now you’ve got your personal, hand polished Petoskey stone!

Wikipedia Petoskey stone
Petoskey Stone

Geology IN

This entry was posted in Geology and tagged , , . Bookmark the permalink.

Leave a Reply