Concretion is a term used in the fields of biology and mineralogy.
A concretion is a solid foreign body that forms in tissue or in an organ, such as gallstones or kidney stones, and sodium urate tophus.
Mineral mass formed by precipitation around a fragment of material. If this material occurs in a pure state, the concretion is white or transparent if its size is small. Impurities contained in the rock, especially iron oxide, are responsible for the ochre colour of concretions.
In mineralogy, a concretion is a mineral mass formed by precipitation. © mendhak, by sa 3.0