Material grinding (also called attrition milling) is the process by which materials are mechanically broken into fine granules and is an essential step in many industrial processes. Considered a subset of cutting, grinding is used in the metal-cutting process. Grinding machinery can be used to reduce the particulate size of various materials with precision, but is most commonly recognized for its uses in the mining industry where it is used to extract valuable metals, such as gold and silver, from surrounding host rock. These tools are not only useful but are also unique. For grinding materials, there are few substitutes for the high ease and efficiency of industrial grinding machines.