sedimentary

Porous limestone (likely fossiliferous or weathered limestone)

Calcite-rich limestone; chiefly calcium carbonate (CaCO₃)

AI-generated identification · may be incorrect

Typically Mohs hardness 3, tan to brown, dull to earthy luster, and very fine-grained to bioclastic texture; weak or absent cleavage as a rock. The cavities may reflect dissolved fossils, shell fragments, or weathering along carbonate-rich layers.

Identified August 28, 2026More sedimentary →

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At a glance

Common name: Porous limestone (likely fossiliferous or weathered limestone)
Scientific name: Calcite-rich limestone; chiefly calcium carbonate (CaCO₃)
Category: sedimentary
Identified: August 28, 2026
Method: Standard

AI Estimated Value

About $1–$20 for a common loose specimen; roughly $20–$100+ if demonstrably fossiliferous, unusually sculptural, or locally significant.

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

Forms from accumulated marine carbonate mud, shells, and skeletal debris, later compacted and cemented; dissolution creates vugs and holes. Exact geological age cannot be determined from the photograph and may range from Paleozoic to recent deposits.

Uses & applications

Used as aggregate, cement and lime feedstock, building stone, and decorative material; porous pieces have limited collector value unless they contain identifiable fossils or unusual textures.

Geological facts

Limestone commonly effervesces vigorously with dilute hydrochloric acid or household vinegar, though weak vinegar reactions may be subtle. Its irregular cavities are more consistent with weathered carbonate rock than volcanic pumice.

Field identification & locations

Likely locations include marine sedimentary basins worldwide; identify it by its light color, relatively soft surface, and acid reaction, while avoiding confusion with porous concrete or tuff. A fresh scratch should be made easily with a steel nail.