Notes. Columns 1-6 list, respectively, the adopted dust species, the key element of each species, the bulk density of the dust grains, the atomic weight of one formula unit, the atomic weight of the key element, and the number of atoms of the key element per formula unit. ^(a)The element with the least abundance is considered the key element among the two. ^(b)Inferred using the amount of Carbon bound in Silicon carbide and according to the formula: ${\mathrm{\Sigma }}_{C,SiC}=\frac{12}{40}{\mathrm{\Sigma }}_{Si}$, where ΣSi is the Si abundance after the formation of Silicates (Zhukovska et al. 2008).