A mill for grinding and/or mixing a material. In one presently preferred embodiment of the present invention, the mill includes a first container rotatably mounted at a first end of a gyration arm. The container rotates about a first axis, and the gyration arm rotates about a second axis. The mill may further include a second container mounted at a second end of the gyration arm. The second container is rotatable about a third axis. As the gyration arm rotates about the second axis, the containers move with the gyration arm. In addition, the containers themselves rotate about their own respective axes thereby greatly enhancing the forces within the containers effecting the grinding and/or mixing. A first motor may be used to rotate the gyration arm, and a second motor may be used to rotate the containers about their respective axes. The mill may be operated in a continuous mode or in a batch mode.