Mafic rocks are rich in magnesium (Mg) and iron (Fe), which are relatively heavy elements. They typically have a higher density than silicic rocks. Examples of mafic rocks include basalt, gabbro, and peridotite.

Silicic rocks are rich in silica (SiO2) and have a lower density than mafic rocks. They typically contain more aluminum (Al), potassium (K), and sodium (Na), which are lighter elements. Examples of silicic rocks include granite, rhyolite, and obsidian.

Density Comparison:

* Mafic rocks: Density ranges from 2.9 to 3.3 g/cm³

* Silicic rocks: Density ranges from 2.6 to 2.8 g/cm³

Therefore, mafic rocks, with their higher content of heavy elements, are generally more dense than silicic rocks.