Abstract: Grinding head for surfacing and polishing stone, marbles and other hard materials including a rotating housing supporting a number of oscillating grinding blocks which during rotation of said housing are pressed against the surface to be treated during simulataneous supply of water to the working zone of said grinding blocks. The apparatus includes a new excenter mechanism for imparting to said grinding blocks an oscillatory tangential movement with respect to said grinding head during rotation thereof. The apparatus also renders possible a forced self-lubrication of bearing surfaces.