Here's why:

* Mafic magma is rich in magnesium (Mg) and iron (Fe). These elements create dark-colored minerals like pyroxene and olivine.

* Mafic magma is also relatively high in silica content, but not as high as felsic magma. This creates denser, heavier rocks.

Examples of mafic igneous rocks include:

* Basalt: A common extrusive (volcanic) rock that forms from quickly cooled lava flows.

* Gabbro: An intrusive (plutonic) rock that forms from slowly cooled magma deep underground.

In contrast:

* Felsic magma is rich in silica and lighter elements like sodium and potassium, resulting in lighter-colored, less dense igneous rocks like granite and rhyolite.