Table showing the various igneous rock types and several of their parameters.


Composition
Percentage
SiO2
Other
elements
Viscosity
Crystallization
temperature
Rocks
produced
Ultramafic
< 40 %
Mg, Fe, Al, Ca
very low
> 1200 °C
peridotite (intrusive)

komatiite (extrusive)
Mafic
40 - 50 %
Al, Ca, Fe, Mg
low
1000 - 1200 °C
gabbro (intrusive)

basalt (extrusive)
Intermediate
50 - 70 %
Al, Ca, Na, Fe, Mg
medium
800 - 1000 °C
diorite (intrusive)

andesite (extrusive)
Silicic
(Felsic)
> 70%
Al, K, Na
high
600 - 800 °C
granite (intrusive)

rhyolite (extrusive)

N.B.: the percentage given for the breaks between the various compositions and rock types are only approximate.