Editing Planetary differentiation (section)

==Chemical differentiation==
Although bulk materials differentiate outward or inward according to their density, the elements that are chemically bound in them [[fractionation|fractionate]] according to their chemical affinities, "carried along" by more abundant materials with which they are associated. For instance, although the rare element [[uranium]] is very dense as a pure element, it is chemically more [[Compatibility (geochemistry)|compatible]] as a trace element in the Earth's light, [[silicate]]-rich crust than in the dense metallic core.<ref>{{Cite journal|last1=Hazen|first1=Robert M.|last2=Ewing|first2=Rodney C.|last3=Sverjensky|first3=Dimitri A.|date=2009|title=Evolution of uranium and thorium minerals|url=https://www.degruyter.com/document/doi/10.2138/am.2009.3208/html|journal=American Mineralogist|language=en|volume=94|issue=10|pages=1293–1311|doi=10.2138/am.2009.3208|bibcode=2009AmMin..94.1293H |s2cid=4603681 |issn=1945-3027|url-access=subscription}}</ref>