ABSTRACT
Amongst the non-skeletal carbonate grains, the variety of coated grains has perhaps received most coverage in the literature. Coated grains comprise a more or less well-defined nucleus, surrounded by a coating of calcareous material, usually fairly finegrained, called the cortex. In many coated grains the cortex is, at least in part, laminated. Many different names and definitions have been used for coated grains (see, for example, Peryt, 1983) with classifications based on size, shape, regularity of concentric laminations, presence of obvious biogenic structures and, often, an interpretation of their origin. There is also, as exists elsewhere in carbonate sedimentology, a discrepancy between what is known from Recent environments and what is found in the geological record.
