Which element is especially abundant in the mantle?

The mantle, which is the thick layer of the Earth located between the crust and the core, is primarily composed of silicate minerals that contain a combination of elements. While oxygen and silicon are indeed abundant and form a significant part of the mineral composition of the mantle, magnesium is particularly notable for its predominance.

Magnesium plays a crucial role in forming the mineral olivine, which is one of the most abundant minerals in the upper mantle. The high presence of magnesium in the mantle contributes to the density and the geochemical behavior of the mantle materials, influencing processes like mantle convection and the formation of magmas.

Iron is also present in the mantle, but it is not as abundant as magnesium in terms of the silicate minerals. Thus, while all the listed elements are important in the context of the mantle's composition, magnesium stands out as especially abundant, making it the best choice in identifying an elemental characteristic of the mantle.