The mesosphere is a layer of the Earth's atmosphere, positioned above the stratosphere and below the thermosphere. However, if you're asking about Earth's internal layers, the term "mesosphere" can also refer to the region of the Earth's mantle beneath the asthenosphere and above the outer core.
In the context of Earth's internal structure, the chemical composition of the mesosphere (mantle layer) is primarily silicate minerals rich in magnesium and iron, such as olivine and pyroxene. The outer core, which is a liquid layer composed mainly of iron and nickel, does not have the same composition as the mesosphere.
Therefore, if we consider the chemical composition among Earth's layers, the mantle layers (particularly the lower mantle, which is often referred to as the "mesosphere" in geological terms) share a similar composition, primarily comprised of silicate minerals, though there may be differences in temperature and physical state.