sedimentary

Weathered iron-rich sandstone or conglomeratic sedimentary cobble

Ferruginous sandstone, possibly polymictic conglomerate

AI-generated identification · may be incorrect

Brown to gray, dull and heavily weathered, with pale quartz/feldspar-looking fragments and darker iron-oxide-rich matrix; likely hardness about 5–7, depending on cement, with no obvious cleavage. Rounded shape indicates water transport and abrasion.

Identified August 9, 2026More sedimentary →

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At a glance

Common name: Weathered iron-rich sandstone or conglomeratic sedimentary cobble
Scientific name: Ferruginous sandstone, possibly polymictic conglomerate
Category: sedimentary
Identified: August 9, 2026
Method: Standard

AI Estimated Value

Typically $1–$10 as an ordinary cobble; up to roughly $20–$50 if locality-specific, unusually attractive, or sold as a labeled geological specimen.

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 sand and gravel, with iron-oxide staining during weathering; the original sediment may be Paleozoic to younger, but age cannot be determined from the photograph. Its rounded form suggests erosion in a river, beach, or glacial deposit.

Uses & applications

Mostly a teaching, landscaping, or collecting specimen; ferruginous sandstone can be used as aggregate or building stone, though this cobble has little commercial value.

Geological facts

The rusty brown color commonly comes from hematite and goethite cement. Bright pale patches may be quartz or feldspar clasts, weathered mineral veins, or surface encrustation.

Field identification & locations

Look for gritty sand-sized grains, a rough fracture, iron staining, and weak layering; a dilute hydrochloric-acid test can reveal carbonate cement if it fizzes. Common in sedimentary terrains and stream gravels worldwide; exact identification requires a fresh break or thin section.