Here's why:
* Mafic minerals are rich in magnesium (Mg) and iron (Fe). These minerals are typically dark in color, giving the rocks their characteristic dark appearance.
* Examples of mafic minerals: Pyroxene, olivine, and amphibole.
* Igneous rocks with high mafic content tend to be denser and have a higher melting point than lighter-colored igneous rocks.
In contrast:
* Felsic minerals (rich in silica, sodium, and potassium) are lighter in color and contribute to the light appearance of some igneous rocks.
Therefore, the darker color of igneous rocks is a visual indicator of their mafic composition.
