Abstract: A coal-mining auger having (a) a hollow, tubular auger head with a spiral or helical coal conveyor mounted therein in concentric relation to the axis of rotation of said auger head, (b) a plurality of coal-cutting bits mounted on said auger head, said bits being orbitally movable with the auger head in circular paths concentric with said axis of rotation, said bits being also concurrently rotatable about their individual axes, and (c) coal-cutting bits which are radially adjustable relative to said axes of rotation. The individually rotatable bits are driven by planetary gear trains which are driven by the main auger shaft.