A vibratory milling machine has a vibratory housing confined to substantially linear reciprocating motion relative to a base, causing a tool carried by the housing to impact a mineral formation or other work piece substantially in a primary milling direction. The vibratory motion may be generated by two or more eccentrically- weighted rotors rotated by a common drive mechanism. The rotors may be arranged in pairs with the rotors of each pair rotating in opposite directions about parallel axes so that lateral oscillations cancel and longitudinal vibrations in the milling direction reinforce one another. In one embodiment, a hydrostatic fluid bearing is provided between the outer surface of each rotor and the housing.