An apparatus for defibrating optically dense glass melts, such as a glass melt from basalt by the jet process, is proposed which is equipped with a feeding mechanism (1) for the melt and defibrating aggregates (2), the feeding mechanism (1) having a feed channel (3) and a subsequent distributing channel (4) with outlet ports (5) to the defibrating aggregates (2). To homogenize the glass temperature in the area before the defibrating aggregates (2) the feed channel (3) has on the bottom side at least in the area adjacent the distributing channel (4) a warming device (8) serving as a thermal barrier or active insulation and advantageously formed as an electric resistance heating device.