sedimentary

Weathered brown stone, possibly chert or iron-stained limestone

Uncertain; likely microcrystalline quartz (SiO₂) chert or calcitic limestone (CaCO₃)

AI-generated identification · may be incorrect

Brown to tan, dull earthy luster, massive and fine-grained, with irregular fractures and a weathered surface. Chert has Mohs hardness ~7 and does not scratch easily; limestone is ~3 and may fizz with dilute hydrochloric acid.

Identified September 6, 2026More sedimentary →

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At a glance

Common name: Weathered brown stone, possibly chert or iron-stained limestone
Scientific name: Uncertain; likely microcrystalline quartz (SiO₂) chert or calcitic limestone (CaCO₃)
Category: sedimentary
Identified: September 6, 2026
Method: Standard

AI Estimated Value

Typically $1–$10 as an ordinary specimen; potentially more if testing reveals unusual texture, fossils, or archaeological significance.

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 as sedimentary rock and later altered by weathering and iron-oxide staining; its geological age and exact formation cannot be determined from the photograph.

Uses & applications

Common chert may be used for aggregate and historically for tools; limestone is used in cement, lime, aggregate, and building stone. This specimen has little commercial or jewelry value without diagnostic testing.

Geological facts

The rounded shape may result from stream transport or natural weathering. Brown coloration commonly reflects hematite or goethite coatings and staining.

Field identification & locations

Test hardness against a steel nail or glass, and apply a drop of vinegar or dilute acid to a fresh surface: strong fizz suggests limestone, while no fizz plus glass-scratching hardness suggests chert. Common worldwide in sedimentary terrains.