Topic summary
Basic rock
Extracted from the Wikipedia article Mafic.
Rocks
Chemically, mafic rocks are sometimes defined as rocks with a silica content between 45 and 55 wt%, corresponding to the silica content of basalt in the TAS classification. Such rocks are enriched in iron, magnesium, and calcium and typically dark in color. In contrast, the felsic rocks are typically light in color and enriched in aluminium and silicon along with potassium and sodium. Mafic rocks also typically have a higher density than felsic rocks. The term roughly corresponds to the older basic rock class.