Optical properties, Q_abs and Q_sca, for spheroid and coated spheroid, parallel (thin lines) and perpendicular (thick lines), for amorphous silicate (a-Sil) particles of a_eff = 150 nm with 5 nm deep a-C confocal mantles, for oblate and prolate particle axis ratios of 1.3 and 2. The key parameters indicate on each sub-plot. The horizontal bands in the lower part of each plot show the ratio of the Q_abs values for DDA/analytic (red) and EMT/analytic (green). The horizontal bands delimit difference factor ranges of 0.9–1.1 (yellow), 0.7–1.3 (grey), and 0.5–2 (orange).