  Chondrites are undifferentiated sediments of material left over from the
earliest solar system and are widely considered as representatives of the
unprocessed building blocks of the terrestrial planets. The chondrites, along
with processed igneous meteorites, have been divided into two broad categories
based upon their isotopic signatures; these have been termed the CC and NC
groups and have been interpreted as reflecting their distinctive birth places
within the solar system. The isotopic distinctiveness of NC and CC meteorites
document limited radial-mixing in the accretionary disk. The enstatite and
ordinary chondrites are NC-type and likely represent samples from inner solar
system (likely $<$4 AU). Measurement and modeling of ratios of refractory
lithophile elements (RLE) in enstatite chondrites establish these meteorites as
the closest starting materials for the bulk of the silicate Earth and the core.
Comparing chondritic and terrestrial RLE ratios demonstrate that the Bulk
Silicate Earth, not the core, host the Earth's inventory of Ti, Zr, Nb, and Ta,
but not the full complement of V.
