sedimentary

Weathered iron-rich limestone or altered volcanic rock

Probable limonite/goethite-bearing calcite rock; exact identification requires testing

AI-generated identification · may be incorrect

Brown-yellow earthy coating and pale gray-white granular areas suggest iron oxides with carbonate or silicate minerals. Likely hardness 3–6, dull to earthy luster, massive texture, and no visible cleavage or crystals; a dilute acid test may effervesce if calcite is present.

Identified September 2, 2026More sedimentary →

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At a glance

Common name: Weathered iron-rich limestone or altered volcanic rock
Scientific name: Probable limonite/goethite-bearing calcite rock; exact identification requires testing
Category: sedimentary
Identified: September 2, 2026
Method: Standard

AI Estimated Value

Approximately $5–$25 for a small, unattributed specimen; more if locality, mineral identity, or attractive botryoidal texture is documented.

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 by weathering and oxidation of an iron-bearing limestone or volcanic protolith, with limonite/goethite accumulating near the surface. Its age cannot be determined from the photograph.

Uses & applications

Primarily a teaching or collector specimen; iron-rich material may be of minor ore interest, while limestone can be used for aggregate or cement if sufficiently pure.

Geological facts

The yellow-brown coloration commonly comes from hydrated iron oxides, especially limonite and goethite. White patches may represent calcite, quartz, or weathering products.

Field identification & locations

Look for a yellow-brown streak, earthy texture, and possible magnetism; test for fizz with dilute hydrochloric acid or vinegar, and compare hardness with a steel nail and glass. Common in weathered outcrops and iron-rich soils worldwide.