Rock Types: Igneous, Sedimentary Metamorphic Rocks | .
> Rock Types: Igneous, Sedimentary Metamorphic Rocks. Rock Types: Igneous, Sedimentary Metamorphic Rocks. ... These are characterized by high content of silica—up to 80 per cent, while the rest is divided among aluminium, alkalis, magnesium, iron oxide, lime etc.. ... The old rocks of the great Indian peninsula are rich in these ...