sedimentary

Weathered vesicular limestone or calcareous tuff

Porous calcite-rich carbonate rock; composition likely predominantly CaCO₃ (calcite), with iron-oxide staining and possible silica/clay impurities

AI-generated identification · may be incorrect

Typically pale gray to tan, earthy and dull, with abundant irregular cavities and rough granular texture; calcite hardness is about Mohs 3, with weak-to-strong effervescence in dilute hydrochloric acid. The specimen appears heavily weathered, so exact identification from the image alone is uncertain.

Identified August 18, 2026More sedimentary →

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At a glance

Common name: Weathered vesicular limestone or calcareous tuff
Scientific name: Porous calcite-rich carbonate rock; composition likely predominantly CaCO₃ (calcite), with iron-oxide staining and possible silica/clay impurities
Category: sedimentary
Identified: August 18, 2026
Method: Standard

AI Estimated Value

Usually $1–$10 for an ordinary fragment; approximately $10–$30 if tied to a documented locality or containing identifiable fossils.

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

Likely formed from deposited carbonate sediment, porous calcareous debris, or carbonate-rich volcanic ash later lithified and weathered; age and precise environment cannot be determined from the photograph. Brown-red areas are probably iron oxides and cavity infillings.

Uses & applications

Common limestone is used for aggregate, cement, lime, and building stone; this porous specimen has little commercial value but may be useful as a teaching or locality specimen.

Geological facts

The prominent holes may represent weathering of shell fragments, gas cavities, or dissolved carbonate grains. Acid reaction, streak, and a fresh broken surface would distinguish limestone from volcanic tuff or highly weathered concrete.

Field identification & locations

Look for calcite grains, soft scratching by a steel knife, and vigorous acid fizz; limestone commonly occurs in marine sedimentary beds worldwide. Avoid assuming it is a meteorite or fossil without laboratory testing.