Describes
magma
that contains lower amounts of
silica
and is generally less viscous and less gas-rich than
silicic
magma. Tends to erupt effusively, as
lava
flows. Includes
andesites
(57-63 percent SiO2),
basaltic
andesites (53-57 percent SiO2), and
basalts
(47-53 percent SiO2).