sedimentary

Calcite-rich limestone, possibly fossiliferous

Limestone composed mainly of calcite (CaCO₃), potentially containing a fragmentary fossil or calcite-filled structure

AI-generated identification · may be incorrect

Light gray to cream, opaque, earthy to weakly crystalline luster, with irregular fracture and possible cleavage surfaces. Calcite is Mohs hardness 3, has perfect rhombohedral cleavage, and reacts vigorously with dilute hydrochloric acid or vinegar.

Identified August 9, 2026More sedimentary →

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At a glance

Common name: Calcite-rich limestone, possibly fossiliferous
Scientific name: Limestone composed mainly of calcite (CaCO₃), potentially containing a fragmentary fossil or calcite-filled structure
Category: sedimentary
Identified: August 9, 2026
Method: Standard

AI Estimated Value

$1-$15 for a common hand specimen; roughly $20-$75 if a clearly identifiable, attractive fossil or crystal feature is present.

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 carbonate mud, shells, or skeletal debris that lithified into limestone; any visible structure may represent a fossil or later calcite vein/cavity filling. The exact geological age cannot be determined from the photograph.

Uses & applications

Used for aggregate, cement, lime, building stone, and soil amendment; attractive pieces may be collected, but this specimen appears primarily of educational rather than gem value.

Geological facts

The pale, blocky surfaces are consistent with calcite-rich material, though the image alone cannot confirm whether the central form is a fossil. A fresh scratch or acid test is more diagnostic than appearance.

Field identification & locations

Common in marine sedimentary sequences worldwide, including the United States, Mexico, the United Kingdom, and Europe. Test an inconspicuous spot with vinegar, inspect for shell symmetry or chambers, and avoid confusing it with marble or gypsum.