sedimentary
Fossil Crab
Decapoda (likely Avitelmessus or Raninidae family)
Hardness: 3-4 (calcite based); Color: Tan, beige, or grey; Luster: Dull or earthy; Crystal structure: Amorphous fossil replacement; Cleavage: None; SG: 2.6-2.8
- Hardness
- 3-4 (calcite based)
- Color
- Tan, beige, or grey
- Luster
- Dull or earthy
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Physical properties
Hardness: 3-4 (calcite based); Color: Tan, beige, or grey; Luster: Dull or earthy; Crystal structure: Amorphous fossil replacement; Cleavage: None; SG: 2.6-2.8
Formation & geological history
Formed through the process of permineralization or replacement within marine sedimentary deposits, often during the Cretaceous or Tertiary periods, as sediment encased organic remains.
Uses & applications
Educational purposes, museum display, and private fossil collecting.
Geological facts
Fossil crabs are often found within concretions—hard, spherical masses of sedimentary rock that form around organic matter. Crabs have been on Earth for over 200 million years.
Field identification & locations
Look for symmetrical carapace structures, segmented legs, or pincers often encased in nodular stones. Common in coastal sedimentary formations or ancient seabed exposures.
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