Editing Geochemistry (section)

===Meteorites===
[[Meteorite]]s come in a variety of compositions, but chemical analysis can determine whether they were once in [[planetesimal]]s that [[melting|melted]] or [[Planetary differentiation|differentiated]].<ref name=Palme/>{{rp|45}} [[Chondrite]]s are undifferentiated and have round mineral inclusions called [[chondrule]]s. With the ages of 4.56 billion years, they date to the [[Formation and evolution of the Solar System|early solar system]]. A particular kind, the [[CI chondrite]], has a composition that closely matches that of the Sun's photosphere, except for depletion of some volatiles (H, He, C, N, O) and a group of elements (Li, B, Be) that are destroyed by nucleosynthesis in the Sun.<ref name=McSween/>{{rp|318}}<ref name=Palme/> Because of the latter group, CI chondrites are considered a better match for the composition of the early Solar System. Moreover, the chemical analysis of CI chondrites is more accurate than for the photosphere, so it is generally used as the source for chemical abundance, despite their rareness (only five have been recovered on Earth).<ref name=Palme/>