The dredging industry has encountered specific problems related to the nature of the rock to be dredged. Rock excavation by dredging is relatively new and problems have occurred that can be ascribed to lack of understanding of rock engineering, for dredging is traditionally and mostly done in soils. Dredgers may be classified according to their basic method of extraction, transportation and deposition. The choice of dredger depends on a number of considerations, related to the type of project, the volume of rock to be excavated and the nature of the rock. Although wear occurs in other parts of the dredging process as well, the interest is mainly on the wear experienced at the cutting front. Abrasive wear is usually related to abrasive minerals present in the soil or rock, of which quartz is the most common. Abrasive wear is usually significant when the abrasive mineral is harder than the tool material.