The present invention relates to surface-mineralized organic fibers comprising organic fibers having a length in the millimeter range, the surface of which is at least partially coated with finely divided alkaline earth carbonate nanoparticles by means of binders based on copolymers comprising as monomers one or more dicarboxylic acids and one or more monomers from the group of diamines, triamines, dialkanolamines or trialkanolamines and epichlorohydrin, a method for producing such surface-mineralized organic fibers, aqueous slurries thereof, their use in papermaking, in surface finishing of paper, plastic, cement and clay surfaces, in paints and varnishes and the use of the inventive binders for coating the organic fibers with nano alkaline earth carbonates.