a-SilFe,FeS (left panels), a-C (middle panels), and a-C:H (right panels) aggregate normalised dust mass opacities at 250 μm as a functionof the number of monomers composing the aggregates, N. Top row: κ(a0, N) for a0 = 0.05 (red), 0.1 (orange), 0.5 (brown), and 1 μm (purple) normalised to κ(a0, N = 1). Middle row: κ(a0 = 0.1 μm, N, P = 20%) normalised to κ(a0 = 0.1 μm, N, P = 0%). Bottom row:κ(oblate monomers, N) in blue and κ(prolate monomers, N) in pink normalised to κ(spherical monomers, N). The filled areas show the scatter of the dust mass opacities for ten randomly chosen aggregate shapes (see Sect. 2.2).