Continuum-divided normalized peak strength over the 10 μm feature for those sources classified as Group I. The continuum between 7.5 and 13.5 μm has been normalized to 1. Leftmost panel: spectra of sources were no detection of a silicate feature is found: (a) Haro 1-6, (b) EM*SR 21, (c) V815 Ori, (d) UX Tau, and (e) HBC 502. From the second from left panel: disks with detected silicate features are shown in ascending order of peak strength: (f) HBC 338, (g) LkHα 330, (h) V395 Cep, (i) HD 142527, (j) GW Ori, (k) DI Cep, (l) BX Ari, (m) EZ Ori, (n) AK Sco, (o) LkHα 310, and (p) V1044 Ori. The scale is indicated in the leftmost panel and is the same for all sources. Spectra are shifted to allow comparison.