Here's why:

* Mafic: Means the rock is rich in magnesium and iron, giving it a dark color.

* Phaneritic: Means the rock has crystals that are large enough to be seen with the naked eye.

Gabbro fits this description perfectly. It is a coarse-grained, dark-colored intrusive igneous rock composed primarily of plagioclase feldspar and pyroxene.