  We compare the elemental depletions in the gas phase of the interstellar
medium (ISM) with the elemental depletions in the rocky material of our Solar
System. Our analysis finds a high degree of chemical complementarity: elements
depleted in the gas phase of the ISM are enriched in the rocky material of our
Solar System, and vice versa. This chemical complementarity reveals the generic
connections between interstellar dust and rocky planetary material. We use an
inheritance model to explain the formation of primordial grains in the solar
nebula. The primary dust grains inherited from the ISM, in combination with the
secondary ones condensed from the solar nebula, constitute the primordial rocky
material of our planetary system, from which terrestrial planets are formed
through the effects of the progressive accretion and sublimation. The
semi-major-axis-dependence of the chemical composition of rocky planetary
material is also observed by comparing elemental depletions in the Earth, CI
chondrites and other types of carbonaceous chondrites.
