* Bridgmanite: This is the most abundant mineral in the lower mantle, making up about 70% of its composition. It's a high-pressure polymorph of (Mg,Fe)SiO₃.
* Ferrosilite: This is a high-pressure polymorph of FeSiO₃.
* Wadsleyite: A mineral with the formula (Mg,Fe)₂SiO₄.
* Ringwoodite: Another mineral with the formula (Mg,Fe)₂SiO₄.
The lower mantle also contains minor amounts of other minerals, including:
* Calcium silicate perovskite: A calcium-rich mineral with the formula CaSiO₃.
* Iron oxides: These include minerals like magnesioferrite (MgFe₂O₄) and ilmenite (FeTiO₃).
* Other trace elements: These can include elements like aluminium, sodium, potassium, and calcium.
The exact composition of the lower mantle varies with depth and location, but the primary constituents remain consistent. These minerals are all extremely dense and stable under the immense pressure and temperature conditions of the lower mantle.
It's important to note that while we can analyze rocks from the upper mantle and the Earth's crust, directly sampling the lower mantle is impossible with current technology. Therefore, our understanding of its composition relies heavily on theoretical modeling and analysis of seismic waves passing through it.