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Calcareous microbialitic laminated thin crust coated calcareous sandstone rocks occurs within depressions in the southern desert of Kuwait. It is few millimeters thick and consists of alternating dark colored calcareous laminae and light colored detritus-rich clayey laminae. Both types of laminae include calcified cyanobacteria and their extracellular polysaccharides (EPS). Authigenic calcite spicules and platelets of micron size agglutinated on EPS are the main constituents of the calcareous laminae. Calcareous and clayey laminae include detrital silt size quartz, feldspars and calcite grains. Alternation of calcareous and detrital-rich laminae, organosedimentary structures, and mineralogy of this crust may suggest that it has been developed as a result of the interaction between micro-organisms (cyanobacteria) and physiochemical conditions during successive wet and dry periods. (C) 2011 Elsevier Ltd. All rights reserved.