Rock Identifier
Fossil Coral (Tabulate Coral (potentially Favosites or Calapoecia)) — fossil
fossil

Fossil Coral

Tabulate Coral (potentially Favosites or Calapoecia)

AI-generated identification · may be incorrect

Hardness: 3-4 (calcite) or up to 7 (if silicified); Color: Tan, yellowish-brown, cream; Luster: Dull to earthy; Structure: Distinguishable vertical tubes (corallites) with horizontal cross-walls (tabulae) visible in the cross-section.

Hardness
3-4 (calcite) or up to 7 (if silicified)
Color
Tan, yellowish-brown, cream
Luster
Dull to earthy
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Physical properties

Hardness: 3-4 (calcite) or up to 7 (if silicified); Color: Tan, yellowish-brown, cream; Luster: Dull to earthy; Structure: Distinguishable vertical tubes (corallites) with horizontal cross-walls (tabulae) visible in the cross-section.

Formation & geological history

Formed in warm, shallow marine environments during the Paleozoic era, specifically the Silurian or Devonian periods (approx. 350-420 million years ago). The specimen represents a colony of polyps that secreted calcium carbonate skeletons.

Uses & applications

Collecting, educational study, decorative aquarium stone, and sometimes used as an index fossil for dating sedimentary rock layers.

Geological facts

This specimen was found near Louisville, KY (38.2°N, 85.7°W), which is world-famous for the Falls of the Ohio State Park, one of the largest exposed Devonian fossil coral reefs in the world. It is a classic regional find.

Field identification & locations

Identify by looking for the repeating geometric or 'honeycomb' tube structures. To distinguish from modern coral, note the density and limestone/chert matrix. Commonly found in creek beds and limestone outcroppings across Kentucky and Indiana.

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