A stone miller is an industrial machine used for grinding hard materials such as stones, minerals, grains, or ores into fine powder or smaller particles. It typically consists of a heavy-duty grinding chamber, rotating grinding stones or rollers, a feed hopper, and a power unit such as an electric motor or diesel engine. The grinding surfaces are made from strong abrasive materials to withstand continuous impact and friction during operation.

In operation, raw materials are fed into the hopper and directed into the grinding chamber where rotating stones or rollers crush and shear them into finer particles. The continuous movement creates pressure and friction that progressively reduces the material size until the desired fineness is achieved. The processed material is then discharged through an outlet for collection. Stone millers are widely used in construction, agriculture, and mineral processing industries for producing consistent and usable powdered materials.