sedimentary

Porous limestone (likely fossiliferous limestone)

Calcite-rich limestone; predominantly calcium carbonate (CaCO₃), possibly bioclastic or reef limestone

AI-generated identification · may be incorrect

Light cream to tan, very porous and earthy, with dull to weakly crystalline luster; calcite hardness is about Mohs 3, with indistinct cleavage in this massive specimen. Likely specific gravity is approximately 2.3–2.7, though abundant pores reduce its apparent density.

Identified September 12, 2026More sedimentary →

Explore Porous limestone (likely fossiliferous limestone) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

At a glance

Common name: Porous limestone (likely fossiliferous limestone)
Scientific name: Calcite-rich limestone; predominantly calcium carbonate (CaCO₃), possibly bioclastic or reef limestone
Category: sedimentary
Identified: September 12, 2026
Method: Standard

AI Estimated Value

About $5–$25 for a common hand specimen; distinctive fossiliferous or unusually sculptural pieces may sell for $30–$100.

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 accumulated marine carbonate mud, shells, or reef debris that lithified into limestone; the cavities may reflect dissolved fossils or weathering. Its precise geological age cannot be determined from the photograph and may range from Paleozoic to Recent uplifted deposits.

Uses & applications

Used as crushed aggregate, cement and lime feedstock, building stone, and decorative material; porous fossiliferous pieces are also collected or used in landscaping and aquaria.

Geological facts

The most useful test is a drop of dilute hydrochloric acid or vinegar: calcite-rich limestone typically effervesces, especially on a fresh surface. Its numerous rounded cavities may be moldic pores from dissolved shells, but no diagnostic fossil is clearly visible.

Field identification & locations

Common in former shallow-marine environments worldwide, including the Mediterranean, Caribbean, Middle East, and many coastal regions. Confirm with acid reaction, a relatively soft surface, and lack of glassy fracture; avoid confusing it with porous concrete or tuff.