Left: residual dust spectra after subtracting the modeled contributions of the amorphous Mg-silicates and featureless components. Each residual spectrum has been normalized to its maximum value. The residuals show features of crystalline Mg-silicates and of SiO₂ (both amorphous and annealed). For comparison, at the bottom of the plot, we have plotted the opacity curves of 0.1 μm-sized forsterite, enstatite, amorphous silica, and annealed silica. The positions of major feature peaks are indicated by vertical dashed lines. The green and purple rectangles highlight spectra with prominent features from forsterite and from annealed silica, respectively. Right: continuum-subtracted spectra at full spectral resolution, showing molecular emission lines. The spectra have been normalized to their maximum value within the plotted wavelength range. Most objects showing strong annealed silica features in their dust spectra have relatively strong CO₂ lines, while those with prominent forsterite features tend to be water-rich.