Table 1: Composition of the dust mixture in the outer regions of a protoplanetary accretion disk according to Pollack et al. (1994). The table shows the fraction of the indicated elements condensed into the different dust species. x denotes the mole fraction of the pure magnesium silicate end members of the solid solution series forming the magnesium-iron-silicates called olivine-type and pyroxene-type, respectively, on the basis of their assumed chemical composition. Only those dust components of the most abundant refractory elements are considered that are the main sources of dust opacity.

Species		Mg	Fe	Si	S	C	x
formula
olivine-type		0.83	0.42	0.63			0.7
Mg2xFe2(1-x)SiO4
pyroxene-type		0.17	0.09	0.27			0.7
MgxFe1-xSiO3
quartz-type				0.10
SiO2
iron			0.10
Fe
troilite			0.39		0.75
FeS
kerogen						0.55
CHON-material