With some informal conversation with a peer of mine, he had suggested that there is evidence (which he couldn't find,but had remembered reading) that there was Silicon in the Earth's core. I referred to him to a rather famous paper by Micheal Drake which says:
"Further, there is no compelling experimental evidence that Si is extracted into the core under present core-mantle boundary conditions. For example, at the base of a high pressure/temperature terrestrial magma ocean, the metal/silicate partition coefficent for Si is approximately $10^{-3}$ to $10^{-2}$"
But since this paper was published 12 years ago, I am wondering if there is any compelling evidence that Si is in Earth's core, and at what concentration it might be? How might it have gotten there?
References
Drake, M., Righter, K., 2002. Determining the composition of the Earth. Nature 416, 39–44.