Coal Ball
“Permineralized peat with cellular preservation”
Coal balls are rounded concretions of calcium carbonate that formed within ancient peat swamps before the peat was compressed into coal. Unlike the coal around them, the organic material inside coal balls was permineralized — individual plant cells are preserved in three-dimensional detail, providing extraordinary windows into ancient forest ecology.
calcite, dolomite, pyrite, permineralized plant tissue, siderite
Illinois Basin (USA), Appalachian coalfields, Lancashire (England), Ruhr District (Germany), Donets Basin (Ukraine)
3-4
Coal balls preserve Carboniferous plant anatomy in such exquisite detail that botanists can count individual chloroplasts in 300-million-year-old cells — a level of preservation far better than any compression fossil.
Test Your Knowledge
Why are coal balls scientifically more valuable than the coal surrounding them for understanding ancient plants?
Photo Attribution
Title: Coal ball (Duquesne Coal, Upper Pennsylvanian; Steubenville West roadcut, Ohio, USA) 1.jpg
Author: James St. John
License: CC BY 2.0
Related Specimens
Recent Specimens
Essexite (Nepheline Monzogabbro)
“Alkaline gabbro with nepheline”
Spodumene
“The lithium mineral powering the future”
Verdite
“Green fuchsite rock from ancient greenstone belts”
Amber
“Fossilized tree resin preserving ancient life”
Limburgite
“Glassy basanite with no feldspar”
Xenotime
“Heavy rare earth phosphate timekeeper”
Charnockite
“The orthopyroxene-bearing granite”
Oilsand (Tar Sand)
“Sand grains coated in heavy crude”
Want to identify rocks yourself?