Comparison of the MAC for the silicate components of cosmic dust models with the MAC of the Mg-rich samples. The MACs are calculated for a prolate grain with an axis ratio a/b = 1.5 in the Rayleigh limit. Left panel: Astrosil (green line) and THEMIS (dark and light blue lines) compared with each of the four Mg-rich silicate samples (dark lines). Right panel: Astrosil (green line) and THEMIS (dark and light blue lines) compared with the average of the four Mg-rich samples (red line) and the average of the X35, X50A, and X50B samples (orange line).