sedimentary

Fossiliferous limestone fragment

Calcitic limestone; mainly calcium carbonate (CaCO₃), possibly with shell or coral debris

AI-generated identification · may be incorrect

Gray-beige, fine-grained, dull to slightly crystalline, with a prominent layered seam and possible fossil texture. Calcite hardness is Mohs 3, with poor-to-indistinct cleavage; specific gravity is about 2.7. Dilute hydrochloric acid or strong vinegar should produce effervescence.

Identified September 21, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from compacted and cemented marine carbonate mud and skeletal debris, commonly during the Paleozoic or Mesozoic, though the exact age cannot be determined from the photograph. The seam may represent bedding, stylolitic pressure-solution, or a mineralized fracture.

Uses & applications

Used for aggregate, cement, lime, building stone, and agricultural soil treatment; attractive fossil-bearing pieces are collected but are rarely used as gemstones.

Geological facts

The specimen appears sedimentary rather than igneous or metamorphic, and the visible band may be a fossil-rich bedding plane or calcite-filled fracture.

Field identification & locations

Look for fizzing in acid, powdery streak, visible shell fragments, and sedimentary layering; common worldwide in former shallow-marine basins. Exact identification requires a close examination of the apparent fossils and a fresh surface.