Definition Of concretion
a hard solid mass formed by the local accumulation of matter, especially within the body or within a mass of sediment.
a mass of small concretions, each built up layer upon layer around some small nucleus
Example Of concretion
A nodule is a type of concretion with a rough and knobby surface.
An offshore marine environment of deposition is suggested for the mudstones, with the concretionary horizons interpreted to represent periods of reduced sedimentation, and early cementation.
Asbestos bodies are asbestos fibers that have been coated with an iron-rich, proteinaceous concretion .
At certain levels, carbonate-rich beds are present, inside which decimetre-scale hard calcareous concretions develop.
At Cresson Quarry, the Kiamichi Formation is 10 m thick and comprises silty marls with concretionary limestone lenses and layers and minor beds of fine sandstone.