1.basalt
2.rhyolite
3.gabbro
4.andesite
5.granite
2.rhyolite
3.gabbro
4.andesite
5.granite
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Basalt. It is the most mafic of the rocks (lacking in silica, high in iron). The reason for this is that when magma rises, it's only moving through the lithosphere before it pops through the surface (the surface beneath the oceans). This means that it really isn't even exposed to silicate minerals. You get rocks like basalt, which are heavy, and form the basic ocean basins (as far is igneous rocks go).
On the other hand, continental crust rises through rocks bearing silica, erupting lighter materials like granite.
Of course, this is a very simplified explanation, but is also correct.
On the other hand, continental crust rises through rocks bearing silica, erupting lighter materials like granite.
Of course, this is a very simplified explanation, but is also correct.