Niobium deficit, FeNi core

The two rare earth elements niobium (Nb) and tantalum (Ta) were the main subject of study in the investigation referred to. Both elements have very similar properties and almost always occur together in our solar system. However, the silicate crust of the Earth contains around 30% less niobium (compared to its sister tantalum). Where are the missing 30% of niobium They must be in the Earth s FeNi core. It is known that the metallic core can only take up niobium under huge pressures, and the conditions necessary for this may have been present on Earth. Analyses of meteorites from the asteroid belt and from Mars show that these do not have a niobium deficit. 

A similar niobium deficit to that on Earth was found on the moon, although the latter s lower mass would preclude the existence of pressures high enough to lead to an absorption of niobium by the FeNi core. It is thus very likely that the moon was formed from material derived from the heavenly body which collided with the Earth and from the proto-Earth s silicate-rich cmst around 4.4 billion years ago. 

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See also in sourсe #XX -- [ ]

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