sedimentary
Fossilized Coral (Favosites)
Favosites (extinct genus of tabulate coral)
Hardness: 3-4 (calcite) or up to 7 (if silicified). Color: Gray, tan, or white. Luster: Dull to earthy. Structure: Honeycomb-like pattern of hexagonal pores (corallites).
- Hardness
- 3-4 (calcite) or up to 7 (if silicified)
- Color
- Gray, tan, or white
- Luster
- Dull to earthy
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Physical properties
Hardness: 3-4 (calcite) or up to 7 (if silicified). Color: Gray, tan, or white. Luster: Dull to earthy. Structure: Honeycomb-like pattern of hexagonal pores (corallites).
Formation & geological history
Formed through the replacement of organic coral structures with minerals (usually calcite or silica) in marine sedimentary environments during the Silurian to Devonian periods (approx. 430-360 million years ago).
Uses & applications
Primarily used as decorative display pieces, educational specimens, jewelry (when agatized), and as a component in limestone for construction.
Geological facts
Commonly known as 'Honeycomb Coral' due to its distinct geometric pattern. Unlike modern corals, these tabulate corals lacked the radiating septa (lines) within their pores.
Field identification & locations
Identify by looking for a repeating hexagonal or 'honeycomb' grid on the surface of a stony matrix. Commonly found in the Great Lakes region (e.g., Petoskey stones are a related type) and limestone quarries in the Midwest USA and UK.
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