fossil

Fossiliferous limestone (likely stromatoporoid/coral limestone)

Calcite-rich carbonate rock, chiefly CaCO₃; visible fossil structures may be tabulate coral or stromatoporoid

AI-generated identification · may be incorrect

Typically gray-brown, dense, and fine- to medium-grained with brown weathering surfaces and lighter fossil cross-sections; calcite has Mohs hardness 3, vitreous to dull luster, and rhombohedral cleavage. Effervesces strongly with dilute hydrochloric acid or vinegar if exposed fresh.

Identified September 3, 2026More fossil →

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At a glance

Common name: Fossiliferous limestone (likely stromatoporoid/coral limestone)
Scientific name: Calcite-rich carbonate rock, chiefly CaCO₃; visible fossil structures may be tabulate coral or stromatoporoid
Category: fossil
Identified: September 3, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a common hand specimen; $30–$150 or more if the fossils are unusually large, well preserved, or professionally polished.

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

Formed from marine carbonate sediment later lithified, with colonial reef organisms preserved as rounded or laminated structures; commonly Paleozoic, though exact age cannot be determined from the image. Burial compaction and cementation produced the solid limestone matrix.

Uses & applications

Used as crushed stone, cement and lime feedstock, aggregate, and decorative stone; attractive fossil-bearing pieces are collected or sold as lapidary specimens.

Geological facts

The concentric or cellular patterns are biological growth structures rather than mineral crystals. Polished surfaces often reveal much sharper fossil detail.

Field identification & locations

Look for acid reaction, relatively low hardness, and fossil textures distinct from random veining; common in ancient shallow-marine limestone regions worldwide, including North America and Europe. Avoid confusing it with chert, which is harder and does not fizz.