What is earth's lower mantle made of?

Question

Hailey Alexander · Accepted Answer

It's made of silicates and oxides. The most abundant elements there are oxygen, silicon, magnesium, iron and calcium.

There are two main differences between the rock found in the lower mantle and the upper mantle: first, the lower mantle is not the same as the core; instead, it is composed of silicate and oxide rocks instead of metal. 1) Elemental composition: rock in the upper and lower mantles has a higher concentration of iron and magnesium and a lower concentration of calcium and aluminum compared to the crust. This is because calcium and aluminum are more likely to form lower-density silicates than iron and magnesium, which causes the former silicates to float up to the crust. 2) Mineral structure: this applies especially to silicates, which are "perovskite silicates" instead of ordinary silicates. In ordinary silicates we see silicon form four covalent bonds to oxygen, filling up the usual "octet" of valence electron states. Under the high pressure inside the lower mantle, however, the silicon atoms will form six bonds making #SiO_6# octahedra (like sulfur does in the "expanded octet" molecule #SF_6#). Here is a description of the Earth's mantle in detail: Mantle_(geology) at https://tutor.hix.ai

Levi Anderson · Answer

Iron and nickel, with a few lighter elements like silicon or oxygen.

The inner core is a solid ball of mostly metal. It is solid because of the pressure of the rest of the Earth around it, even though it is at 5700K and should be liquid if it were at normal pressure. Its pressure is actually about 3,500,000 atmospheres. Scientists have tested the density of the core by firing waves at it and measuring their reaction, and found that actually a pure nickel-iron compound is more dense than the core, meaning that the core has lighter elements in it, probably carbon, oxygen or silicon.

Nova Adams · Answer

undefined The lower mantle is primarily composed of silicate minerals, with the most abundant being magnesium and iron-rich silicates such as perovskite and magnesiowüstite.