A novel polymer is provided as the condensation reaction product of a non-aqueous mixture of a phenol and an aldehyde in a molar ratio of about 0.5 to 1 phenol to aldehyde, containing refractory fibers, such as carbon, graphite, silica, having an aspect and metal oxides and silicates, which fibers have an aspect ratio of about 10. The phenol is selected from metacresol, orthocresol, 3,5-dimethylphenol, resorcinol and substituted resorcinols, the preferred material being mostly resorcinol. The aldehyde is selected from furfural and mixtures of furfural and paraformaldehyde. The condensation polymerization reaction can be effected by adding an acid catalyst to the mixture or by employing a curing agent which provided a polyfunctional amine reactive with either or both the aldehyde and the phenol.