Mafic Vs. Felsic
Mafic is a term that describes a silicate rock or mineral that is rich in magnesium and iron and has a lower silica content (45 – 52%). They are usually dark in colour and a relative density of greater than 3. Common rock-forming mafic minerals include olivine, augite, hornblende, and biotite. Common mafic rocks include basalt, dolerite and gabbro.
Mafic/basic/pahoehoe magma has a low viscosity as it has a lower silica level. This means that eruptions are less explosive and the lava escaping has a smooth or ropy surface. The lava can also travel a long way because it is more fluid and has a high temperature (in excess of 950°C).
^ Mafic lava flow