Shock-wave data as evidence of the presence of carbon in the Earth’s core and lower mantle

The standard density and average atomic weights of hypothetical materials contained in the inner layers of the Earth are calculated from results of shock-wave studies using a previously proposed method for determining the velocity of sound in materials at high pressures and density, and from seismic data. These data turned out to be sufficient to refine the elemental composition of the Earth’s interior. It is shown that the iron-nickel core of the Earth should contain $\approx$10% (by weight) carbon, partly in the diamond phase. According to the calculations, the lower mantle can contain up to 20% carbon, which probably comes from the core.