Silt and clay-grade carbonate minerals (calcite, aragonite) as interstitial sediment between the grains (Wright, 1992). It appears dark in transmitted light due to the fine grain size. Previous authors have used different terms and crystal-size ranges to define the carbonate mud matrix.
Microcrystalline carbonate matrix
Chemical (abiotic/physico-chemical or biogenic) carbonate precipitates from aqueous solution.
Microcrystalline carbonate precipitated in situ (abiotic or biologically induced/influenced by microbial mats) as micrite or micritic peloids embedded in microsparite (clotted peloidal micrite)
Crystals of calcite and aragonite > than 62 μm (they can vary in size and shape) that appear hyaline/transparent in transmitted light. Crystal fabric and mineralogical composition are indicative of diagenetic environments (marine, meteoric, burial).
Primary precipitate or due to neomorphic recrystallization of micrite
Replacive dolomite crystals over calcite or dolomite cement varying in size and shape according to the diagenetic environment. Rare primary dolomite.