sedimentary
Fossilized Coral (Petoskey-like or Favosites)
Anthozoa (Fossilized Coral)
Hardness: 3-4 (Calcite-based) to 6.5-7 (if Silicified); Color: Tan, beige, or white; Luster: Dull to waxy; Structure: Visible honeycomb or polyp patterns (corallites); Specific Gravity: 2.6-2.7.
- Hardness
- 3-4 (Calcite-based) to 6
- Color
- Tan, beige, or white
- Luster
- Dull to waxy
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 3-4 (Calcite-based) to 6.5-7 (if Silicified); Color: Tan, beige, or white; Luster: Dull to waxy; Structure: Visible honeycomb or polyp patterns (corallites); Specific Gravity: 2.6-2.7.
Formation & geological history
Formed during the Devonian or Silurian periods (350-450 million years ago) when warm, shallow seas covered much of the interior of North America. These are the mineralized remains of ancient marine coral colonies.
Uses & applications
Commonly used in jewelry (pendants and beads), lapidary art, paperweights, and as educational geological specimens for collectors.
Geological facts
These fossils represent organisms that lived millions of years before dinosaurs. While Michigan is famous for Petoskey stones (Hexagonaria), similar Favosites fossils (honeycomb corals) are found globally in Paleozoic rock layers.
Field identification & locations
Identified by the distinct geometric pattern of pores or 'cells' on the surface of the stone. Often found on beaches of the Great Lakes or in limestone quarries and road cuts. Polishing often reveals more intricate details.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary
Sandstone (with man-made markings)
Arenite (composed primarily of Quartz, SiO2)
sedimentary