Silicon in Iron Meteorites and the Earth's Core

Abstract

WE have searched for silicon in the metal phase of several iron meteorites in an attempt to test those Earth models which assume that silicon occurs as a major component in the core of the Earth1,2. The experimental technique was activation analysis, based on the fast neutron reaction 28Si(n,p)28Al. This reaction is known to be3 an important contaminant in the determination by the slow-neutron induced reaction 27Al(n,γ)28Al of Al in stone meteorites, in which the silicon content is well known and in which the observed 28Al activity can be corrected for the contribution from silicon. In the iron meteorites, any 28Al activity would have to be attributed to an unknown mixture of silicon and aluminium. As it turns out, however, no activity is seen and so limits can be set to both the aluminium and silicon contents of the iron meteorites.