Petoskey Stone
A variety of Coral
Uncommon
What is Petoskey Stone?
Petoskey Stone can be found in only one location in the world and that’s along the Great Lake’s shores of Michigan’s lower peninsula. In 1965, this stone unique to Michigan (USA) became its official state stone. Some 350 million years ago, these fossil rocks were living colonies of corals named “rugose”.
Optical Properties
- Refractive Index
- 1.486-1.658
- Birefringence
- 0.160-0.172
- Pleochroism
- None
- Optical Character
- Uniaxial negative
Petoskey Stone Market Value Calculator
Estimate the market value of Petoskey Stone using size, quality, and finish. This preview calculator is for quick context and is not a formal appraisal.
Petoskey Stone Localities Map
See where Petoskey Stone is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Map preview
North ZoneCentral RidgeSouth Basin
Key Characteristics
Composition of Petoskey Stone
Calcite
More Images
© James St. John
© The original uploader was Jtmichcock at English Wikipedia.
Later versions were uploaded by Rmhermen at en.wikipedia.
Quick Facts
Physical Properties
- Hardness (Mohs)
- 3
- Density
- 2.3 - 2.7 g/cm³
- Crystal System
- Trigonal
Chemical Properties
- Chemical Formula
- CaCO3
Also Known As
Petoskey StoneHexagonaria Coral
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