Talk:Petoskey stone

needs a picture. MPS 20:44, 15 July 2005 (UTC)

Sorry about the Massachusetts edit. Just saw it there on the other link, assumed whoever put it there knew what they were talking about. --Lurlock 13:49, 6 July 2006 (UTC)

Petoskey Stones
There is an important piece missing in the Wikipedia information regarding Petoskey Stones. Namely that the land that is now Michigan was close to the equator during the Devonian period. This is why so much of it was covered by a shallow, warm sea. Here's more information:

We must first go back 355-415 million years ago to the Devonian Period. Devonian is one of the eleven geologic periods that divide the last 545 million years of earth's history, based on the fossil record. The Devonian Period was about 100 million years before the dinosaurs roamed the earth, and the land that is now Michigan was at that time positioned near the equator and was completely covered by a warm shallow sea that extended from the Gulf of Mexico through Michigan and into Canada. On this sea bottom were corals (Hexagonaria percarinata), mostly composed of calcium carbonate, much like the corals in seas and oceans today. About 70,000 years ago, the Wisconsin Ice Sheet, which was about 2 miles thick moved across the Lower Peninsula and carved out the basins of the Great Lakes. The glacier picked up the coral colonies and that had weathered their way to the surface, froze to them, and incorporated them within its body, and carried them south. In the northern quarter of the state it gouged out and freed billions or trillions more from the calcareous shales in which they were entombed. As the glacier moved across the state, it left tremendous numbers of coral colonies scattered across Michigan and undoubtedly carried some into Illinois, Indiana and Iowa. When the ice melted, the Petoskeys were left behind as glacial eratics - stones carried by the glacier to places they didn't originate from. Similar types of fossils are found in New York, Alaska, England and Germany, and many other parts of the world, but ours are unique because of the fine texture which lends itself to polishing. Here in Michigan the corals were invaded at some time by crude oil and it is the oil that gives the stones their soft brown color, often with spot-like concentrations of the oil at the center of the cups. It is the amount of crude oil in a stone that determines the lightness or darkness of its color. If you put a Petoskey stone under a black light, it will fluoresce blue indicating the presence of crude oil. Both the City of Petoskey and the stones owe their name to an 18th century Ottawa Indian legend. According to the legend, Chief Nea-a-tooshing was so impressed by rays of sunshine on the face of his newborn son that he named the child "Pe-tos-e-gay", which meant "Sun Beams of Promise". Petosegay lived up to his promise and became a great fur trader, merchant and chief. In the summer before his death, the city of Petoskey (the English version of Petosegay) was settled with a population of 50 - 60 people. On June 18, 1965 Governor Romney signed House Bill 2297, making the Petoskey Stone the official Michigan State Stone. Appropriately, Miss Ella Jane Petoskey, the only living relative of Ottawa Indian Chief, Petosegay, was present at the signing. The stone most likely received its name because it was first used by the Ottawa Indians as beads and ornaments during Chief Petosegay's time. Later they were found and sold as souvenirs and curios to the tourist trade around the City of Petoskey. 76.29.123.84 (talk) 21:06, 9 September 2008 (UTC) Jim

Hexagonaria percarinata
The Geological Society of America from 1987 clearly says: "Hexagonaria percarinata (Fig. 4) is more commonly known as the “Petoskey Stone.” The “Petoskey Stone” is the official stone of the state of Michigan. Hexagonaria percarinata was known by many earlier American paleontologists as Acervularia profunda and Cyathophyllum davidsoni. In the recent past it was usually identified as Prismatophyllum davidsoni." (emphasis added) Clearly this indicates that Prismatophyllum davidsoni is an incorrect earlier name. And 1987 is a more recent source than the 1981 source which it is not apparent whether it mention Petoskey stones at all. Hexagonaria percarinata was scientifically named in 1969. That same source (from 2000) indicates "At least seven different species of the genus Hexagonaria are found in Devonian rocks in Michigan. Hexagonaria corals are found in Iowa, Indiana, Illinois, Ohio, New York, Canada, Germany, England and even in Asia." Rmhermen (talk) 16:00, 4 November 2010 (UTC)


 * I just noticed there is an article for Hexagonaria, which should probably be linked instead of the redlink to Hexagonaria percarinata, but figured I'd post since the naming issue was up for discussion.  The first reference in that article is a 1970 paper from U-M which discusses this subject in detail and shows images of a bunch of those other species.  I had no idea there were so many species of Hexagonaria other than percarinata that were found in northern MI.  I'd always attributed subtle differences in appearance to different conditions during to the fossilization process.   But if this (older) paper is still to be trusted, it seems there are actually a bunch of very similar looking species found in the area...?     I think it would be helpful to have assistance from an expert on this topic...  --Dfred (talk) 17:22, 4 November 2010 (UTC)

Agate?
Is this stone an agate? The Agate article says that the fossilization process turns it into one but this article doesn't mention anything about it. Could someone who understands minerals better than I do clarify the issue? Asarelah (talk) 14:21, 4 April 2016 (UTC)