sedimentary

Likely bituminous coal

Coal, predominantly maceral-rich carbonaceous material (composition varies)

AI-generated identification · may be incorrect

Black to dark brown, dull to mildly shiny, with irregular fracture and no visible crystals; hardness is variable, commonly about 1–3 Mohs. The image alone cannot confirm coal versus another dark rock or carbonaceous material.

Identified October 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Coal forms when plant matter accumulates in oxygen-poor wetlands, is buried, and altered by heat and pressure over geologic time; age depends on the deposit.

Uses & applications

Coal is used as fuel and in coke production for steelmaking; suitable specimens may also be collected or displayed.

Geological facts

Coal is an organic sedimentary rock, not a mineral, and its rank ranges from lignite through bituminous coal to anthracite.

Field identification & locations

A black streak, relatively low density, and tendency to smudge or fracture can support identification; confirm with a streak test and context, since appearance is inconclusive. Major deposits occur worldwide, including China, the United States, India, Australia, and Russia.