Effect of grain size on the mid-infrared and 69 μm bands of 150 K forsterite grains. The grey, blue, green, red, teal, purple, and yellow curves are for forsterite with grain sizes of 0.001, 0.1, 1, 3, 5, 7 and 9 μm, respectively. The opacities are calculated for grains with a DHS shape distribution (Min et al. 2005), using the optical constants of Suto et al. (2006). The dashed black line are the opacities when calculated with CDE (Continuous Distribution of Ellipsoids; Bohren & Huffman 1983).