For submicrometer-sized particles of the carbonaceous chondrite Nogoya and, for comparison purposes, also of terrestrial chamosite, the mass absorption coefficients have been derived from laboratory spectra for the wavenumber range 250-1300 cm-1. Using these data the expected spectrum of an infrared source has been calculated under simple model assumptions and compared with the observed flux from the infrared source OH 26.5+0.6. Although certain discrepancies are left in the 20-μm region it is concluded that phyllosilicates, especially such occurring in carbonaceous chondrites, are interesting candidates for the material of interstellar grains. © 1979 D. Reidel Publishing Co.