sedimentary

Fossiliferous limestone

Calcitic limestone; predominantly calcium carbonate (CaCO₃), commonly as calcite with fossil fragments

AI-generated identification · may be incorrect

Typically light gray, fine- to medium-grained, dull to subtly crystalline, with darker fossil or shell impressions; Mohs hardness 3, poor cleavage, and specific gravity about 2.3–2.7. Effervesces strongly with dilute hydrochloric acid or vinegar if the surface is freshly scratched.

Identified September 4, 2026More sedimentary →

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At a glance

Common name: Fossiliferous limestone
Scientific name: Calcitic limestone; predominantly calcium carbonate (CaCO₃), commonly as calcite with fossil fragments
Category: sedimentary
Identified: September 4, 2026
Method: Standard

AI Estimated Value

$1–$10 for a common field specimen; approximately $10–$50 or more if fossils are clearly preserved, attractive, and locality-documented.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

A marine sedimentary rock formed by accumulation and cementation of carbonate mud, shells, and skeletal debris; its age cannot be determined reliably from the photograph and may range from Paleozoic to Cenozoic. The visible rounded structures may be fossil fragments, although weathering can produce similar patterns.

Uses & applications

Used as crushed stone, aggregate, cement and lime feedstock, building stone, and occasionally as a fossil-collecting specimen; generally unsuitable for jewelry.

Geological facts

Fossiliferous limestone often preserves marine organisms such as brachiopods, bivalves, crinoids, or corals. Acid testing and a close examination of the shapes are more diagnostic than color alone.

Field identification & locations

Common in former shallow-marine basins worldwide, including the Caribbean, Mediterranean, Gulf Coast, and many continental sedimentary regions. Confirm identification by acid reaction, relatively low hardness, and recognizable shell or skeletal textures; avoid acid on valuable specimens.