MINERALS/Carbonates 527 reflect different philosophical approaches to the naming and genesis of carbonate rocks, are the most commonly used schemes Usage of one or the other of these schemes is a matter of personal preference and the type of study that is being undertaken Fundamentally, names derived from Folk’s scheme reflect the dominant allochem (e.g., ooid, pellet, bioclast, or lithoclast) and the micrite matrix or spar calcite cement found between the allochems (Figure 4) For example, an oomicrite refers to a rock formed of ooids embedded in micrite matrix, whereas an oosparite refers to a rock formed of ooids embedded in a spar calcite cement Dunham’s scheme is based on the depositional texture of the rock and makes no specific reference to the allochems, the matrix, or the cement (Figure 5) The progression from mudstone to wackestones to packstone to grainstone reflects, for example, a progressive decrease in the amount of mud (i.e., micrite) and hence ever-increasing energy levels This scheme was Figure Folk’s classification system for carbonate rocks Figure Dunham’s classification system for carbonate rocks The diagrams illustrating the various structures are labelled using the terminology subsequently introduced for different types of boundstones