sedimentary

Knightia Fossil in Limestone

Knightia eocaena in micritic limestone

AI-generated identification · may be incorrect

Hardness: 3-4 (matrix); Color: Tan/buff matrix with dark brown fossils; Luster: Dull/earthy; Fine-grained sedimentary structure with visible skeletal carbonizations.

Hardness: 3-4 (matrix)
Color: Tan/buff matrix with dark brown fossils
Luster: Dull/earthy

Identified March 18, 2026More sedimentary →

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Physical properties

Hardness: 3-4 (matrix); Color: Tan/buff matrix with dark brown fossils; Luster: Dull/earthy; Fine-grained sedimentary structure with visible skeletal carbonizations.

Formation & geological history

Formed during the Eocene epoch (approx. 52 million years ago) in the Green River Formation. Fossilization occurred in a freshwater lake system (Fossil Lake) where fish died and were buried in low-oxygen fine silt.

Uses & applications

Educational specimens, museum displays, home decor, and high-value items for fossil collectors.

Geological facts

Knightia is the state fossil of Wyoming. These specimens are often so well-preserved that soft tissues and individual scales can be observed under a microscope.

Field identification & locations

Identify in the field by looking for layered shale or limestone outcroppings in southwestern Wyoming. Collectors look for 'splits' along bedding planes that reveal dark organic silhouettes of fish.