sedimentary
Likely coal (possibly anthracite)
Coal, a carbon-rich sedimentary rock; anthracite is predominantly carbon
AI-generated identification · may be incorrectBlack to dark gray, irregular and fractured, with a dull-to-glassy luster; hardness varies from about 1–3 for softer coal to 2.5–3 for anthracite. The image does not show enough detail to confirm coal rank or mineral composition.
Identified More sedimentary →
Explore Likely coal (possibly anthracite) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Black to dark gray, irregular and fractured, with a dull-to-glassy luster; hardness varies from about 1–3 for softer coal to 2.5–3 for anthracite. The image does not show enough detail to confirm coal rank or mineral composition.
Formation & geological history
Formed from buried and compacted plant matter in ancient swamp environments; heat and pressure over geologic time produced coal. The specimen’s age and formation cannot be determined from the image.
Uses & applications
Coal is used as fuel and, after processing, in steelmaking; this rough piece has little apparent commercial or jewelry use.
Geological facts
Anthracite is the hardest, highest-carbon coal and burns with less smoke than lower-rank coal.
Field identification & locations
Its black color and uneven, sometimes shiny fracture surfaces are consistent with coal, but identification is uncertain from a photograph. Check whether it is lightweight, brittle, and leaves a dark streak; common coal deposits occur in sedimentary basins worldwide.
More like this
Other sedimentary specimens
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary