During lithification of Recent carbonate sediments there is progressive elimination of high magnesian calcite and aragonite and formation of low magnesian calcite. Low magnesian calcite is precipitated as interparticle cement and forms a drusy calcite mosaic. Mineralogic and textural changes are controlled by pH and salinity of water. Lithification occurs in subaerial conditions and in the subsurface; marine conditions are not conducive to lithification. Processes of aragonite dissolution do not always form a stage in lithification. It is inferred that change from aragonite to calcite in many rocks is a paramorphic replacement. Dolomite forms under three depositional-diagenetic environments--intertidal zone of pellet mud and algal mats, interface, and replacement of calcite-infilled molds of original aragonite.