sedimentary

Likely weathered limestone or calcitic marble

Calcite (CaCO₃), probably micritic limestone; marble is a possible metamorphic alternative

AI-generated identification · may be incorrect

Pale gray-white, dull to weakly earthy luster, fine-grained and irregularly fractured, with rusty iron-oxide staining. Calcite has Mohs hardness 3, rhombohedral cleavage, and typically fizzes strongly with dilute hydrochloric acid; exact texture is difficult to confirm visually.

Identified September 5, 2026More sedimentary →

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At a glance

Common name: Likely weathered limestone or calcitic marble
Scientific name: Calcite (CaCO₃), probably micritic limestone; marble is a possible metamorphic alternative
Category: sedimentary
Identified: September 5, 2026
Method: Standard

AI Estimated Value

About $1-$10 as an ordinary loose specimen; potentially $10-$30 if it has unusual texture, provenance, or collecting interest.

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

Limestone forms from accumulated carbonate mud or biological material, commonly during marine sedimentation; marble forms when limestone is recrystallized during metamorphism. No geological age can be determined from the photograph.

Uses & applications

Crushed limestone is used for aggregate, cement, lime, and soil conditioning; high-quality limestone or marble is used for building stone and sculpture. This irregular specimen has limited commercial value.

Geological facts

Calcite is a major carbon-storage mineral and can show obvious effervescence in acid. The orange-brown patches are likely limonite or other iron oxides rather than the primary rock.

Field identification & locations

Likely occurrences include marine sedimentary basins and limestone quarries worldwide. Test a fresh surface with vinegar or dilute hydrochloric acid, inspect grain size, and compare hardness with a copper coin; avoid destructive testing if it is a valued specimen.