sedimentary

Coal (likely Bituminous or Lignite)

Organic Sedimentary Rock (Carbonaceous)

AI-generated identification · may be incorrect

Hardness: 1-2.5 on Mohs scale; Color: Black to dark brown; Luster: Dull to sub-vitreous; Structure: Amorphous/Organic; Cleavage: None (conchoidal fracture); Specific Gravity: 1.1–1.5

Hardness: 1-2
Color: Black to dark brown
Luster: Dull to sub-vitreous

Identified May 10, 2026More sedimentary →

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Physical properties

Hardness: 1-2.5 on Mohs scale; Color: Black to dark brown; Luster: Dull to sub-vitreous; Structure: Amorphous/Organic; Cleavage: None (conchoidal fracture); Specific Gravity: 1.1–1.5

Formation & geological history

Formed from the remains of prehistoric vegetation (peats) buried under high pressure and heat over millions of years, primarily during the Carboniferous period.

Uses & applications

Primarily used as a fuel source for electricity generation and industrial steel production (coke). Collector value is mostly for educational or historical purposes.

Geological facts

Coal is often referred to as 'buried sunshine' because it stores solar energy captured by plants millions of years ago. It is the largest source of energy for electricity generation worldwide.

Field identification & locations

Identify by its light weight compared to stone, black streak when rubbed on ceramic, and its tendency to be brittle and soil hands with black dust. Common in basin regions with sedimentary layers.