sedimentary

Weathered limestone or calcareous sandstone

Calcite-rich carbonate rock, chiefly calcium carbonate (CaCO₃), possibly with quartz grains

AI-generated identification · may be incorrect

Pale beige, dull to slightly earthy luster, fine-grained and strongly weathered; likely Mohs hardness 3 if limestone, or 4–7 if quartz-rich sandstone. No visible crystals or cleavage; porous, irregular texture.

Identified September 5, 2026More sedimentary →

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At a glance

Common name: Weathered limestone or calcareous sandstone
Scientific name: Calcite-rich carbonate rock, chiefly calcium carbonate (CaCO₃), possibly with quartz grains
Category: sedimentary
Identified: September 5, 2026
Method: Standard

AI Estimated Value

Typically $1–$10 as an ordinary specimen; up to about $20 if unusually textured, fossiliferous, 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 carbonate mud, shell debris, or cemented sand in sedimentary environments, commonly during the Paleozoic–Cenozoic. The rounded shape and surface texture likely result from water or abrasion weathering.

Uses & applications

Crushed limestone is used for cement, aggregate, soil treatment, and construction; sandstone is used as building stone. This individual specimen has little jewelry or commercial value.

Geological facts

A drop of dilute hydrochloric acid or household vinegar may fizz strongly on limestone, though weak vinegar can be inconclusive. Sandstone may show gritty texture and leave visible quartz grains.

Field identification & locations

Common in sedimentary terrains worldwide, especially riverbeds, beaches, quarries, and limestone regions. Field identification requires checking acid reaction, graininess, and streak; the image alone cannot distinguish limestone from calcareous sandstone confidently.