The invention relates to a mining device that is used at the face of a mine, said device comprising a sensor that is mounted on the planer for identifying the rock and transmitting rock data for no more than two measuring points per extraction unit via radio to each extraction control device. The measuring signals of adjacent measuring points are evaluated with respect to the prevalence of rock or coal. Based on said evaluation, the tilting unit that is common to the measuring points is controlled with regard to the raising or lowering of the planer. Each tilting unit is allocated an inclinometer, whose measured value of the inclination of the channel in the transversal direction of the latter is fed to the extraction control device and compared with the tilt signal that is generated by the evaluation. Each inclinometer is equipped with a radio transmitter for the radio transmission of the inclination signals to the assigned extraction control device. Each inclinometer is equipped with a power supply battery, which is activated by a radio signal of a transmitter that is provided on the planer and is deactivated after a time lapse.