[1][2] The term was coined in 1959 by Robert Folk for his carbonate rock classification system.
In the Folk classification micrite is a carbonate rock dominated by fine-grained calcite.
Carbonate rocks that contain fine-grained calcite in addition to allochems are named intramicrite, oomicrite, biomicrite or pelmicrite under the Folk classification depending on the dominant allochem.
The origin of micrites is still a problem in carbonate sedimentology due to the non-uniqueness of the processes generating it.
In lakes and some marine environments, lime mud that could become micrite can form chemically or biochemically through whiting events, whereas in warm stratified marine waters it might be forming chemically.