Abstract: Mineral fibers made of natural basalt materials are produced by preheating basalt to a temperature of between 150 and 900° C., loading the preheated basalt into a melting furnace, melting the basalt to form a glass mass, moving the melted glass mass through a stabilization zone of the melting furnace until a fiber production temperature of tmelt+(50-250° C.) is reached, further stabilizing the glass mass in a feeder at a temperature of 1250 to 1450° C. to obtain a glass mass having the composition 1 Al 2 ⁢ O 3 + SiO 2 CaO + MgO ≥ 3 ⁢   ⁢ FeO Fe 2 ⁢ O 3 ≥ 0.5 2 ⁢ Al 2 ⁢ O 3 + SiO2 2 ⁢ Fe 2 ⁢ 0 3 + FeO + CaO + MgO + K 2 ⁢ O + Na 2 ⁢ O > 0.