Here's why:

* Mafic Composition: Basalt is a mafic rock, meaning it is rich in magnesium and iron. The term "mafic" comes from the minerals magnesium and ferric.

* Origin: Basaltic rocks form from the cooling of magma that originated deep within the Earth's mantle. The mantle is rich in iron and magnesium, which are incorporated into the magma.

* Mineral Content: Common minerals in basalt include:

* Pyroxene: A silicate mineral containing magnesium, iron, and calcium.

* Olivine: A silicate mineral rich in magnesium and iron.

* Plagioclase Feldspar: A silicate mineral that can contain varying amounts of sodium and calcium.

In contrast to felsic rocks, which are high in silica, potassium, and sodium, basaltic rocks are lower in silica and higher in iron and magnesium.