sedimentary

Weathered sedimentary cobble, likely limestone or calcareous sandstone

Indeterminate carbonate-rich clastic rock; possibly micritic limestone or calcarenite

AI-generated identification · may be incorrect

Tan-gray, rounded and heavily weathered, with dull earthy luster and porous granular texture. Estimated Mohs hardness 3–5; no visible crystals or cleavage, and likely low-to-moderate density. Effervescence with dilute hydrochloric acid would distinguish limestone from sandstone.

Identified September 13, 2026More sedimentary →

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At a glance

Common name: Weathered sedimentary cobble, likely limestone or calcareous sandstone
Scientific name: Indeterminate carbonate-rich clastic rock; possibly micritic limestone or calcarenite
Category: sedimentary
Identified: September 13, 2026
Method: Standard

AI Estimated Value

Typically $0–$10 as an ordinary field cobble; potentially $10–$30 if it contains attractive fossils or unusual textures.

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

Probably formed from cemented carbonate mud, shell debris, or sand, then rounded by water and altered by surface weathering. Exact geological age and provenance cannot be determined from the photograph.

Uses & applications

Common limestone is used for aggregate, cement, lime, and building stone; sandstone is used for masonry and paving. This individual cobble has little commercial or collector value.

Geological facts

The rounded shape indicates transport by a stream, beach, or glacial process. Weathering has softened the surface and obscured its original grain or fossil content.

Field identification & locations

Inspect a freshly broken surface with a hand lens: limestone is usually fine-grained and fizzes strongly in acid, while sandstone shows visible quartz grains and little reaction. Common worldwide in sedimentary terrains and river or beach gravels.