Sorting of chondrite components

Physical processes that separate one type of material from another can also produce chemical and isotopic fractionations. Several important chemical properties of chondrites probably reflect some sort of physical fractionation process. 

Bulk compositions of two CM chondrites normalized to Cl abundances. Elements are plotted in order of decreasing volatility from left to right. Lithophile elements are shown with open symbols, siderophile elements with black symbols, and chalcophile elements with gray symbols. The elements form two relatively flat plateaus at -1.25 x Cl and -0.6 x Cl. Note that there is no fractionation between lithophile, siderophile, and chalcophile elements. CM data from Kallemeyn and Wasson (1981) and Krahenbiihl et al. (1973). 

Physical fractionation of silicate components (refractory CAIs and an olivine-rich component, perhaps chondrules) are suggested by trends in Si/Al and Mg/Al in bulk chondrites. 

---