sedimentary

Weathered coal-bearing sedimentary rock (likely shale or mudstone with coal fragments)

Carbonaceous shale/mudstone; predominantly clay minerals, quartz, and organic carbon

AI-generated identification · may be incorrect

Usually dark gray to black, dull to slightly earthy, very fine-grained, and fissile or crumbly; hardness about 2–4 Mohs. The visible angular black-brown fragments may be coal or carbonaceous shale, while pale grains may be quartz or feldspar.

Identified August 16, 2026More sedimentary →

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At a glance

Common name: Weathered coal-bearing sedimentary rock (likely shale or mudstone with coal fragments)
Scientific name: Carbonaceous shale/mudstone; predominantly clay minerals, quartz, and organic carbon
Category: sedimentary
Identified: August 16, 2026
Method: Standard

AI Estimated Value

Generally $0–$5 for loose common fragments; attractive fossiliferous or collectible coal-shale specimens may sell for $10–$50.

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 compacted, organic-rich mud in low-energy swamp, lake, or marine settings, commonly associated with coal seams; ages range widely, often Paleozoic to Mesozoic. The specimen appears heavily weathered and embedded in a rough outdoor surface.

Uses & applications

Used locally as fuel when coal-rich and, historically, for brick or cement manufacture; ordinary weathered pieces have little practical or jewelry use.

Geological facts

Coal-bearing shales commonly preserve plant debris and can generate hydrocarbons during burial. Coal typically breaks into shiny or dull black, lightweight fragments with brown streaks.

Field identification & locations

Identify by its layered texture, low density, dark carbonaceous streak, and tendency to split or crumble; a streak test and close inspection for bedding help distinguish it from basalt or slag. Common in sedimentary basins and coal districts.