In its oxide or silicate form, silicon is used to make concrete, bricks, glass, ceramics, and soap. Silicon metal is also the base material for making silicones used in such products as synthetic oils, caulks and sealers, and anti-foaming agents.
Intrusive igneous rocks crystallize below Earth's surface, and the slow cooling that occurs there allows large crystals to form. Examples of intrusive igneous rocks are diorite, gabbro, granite, pegmatite, and peridotite. Extrusive igneous rocks erupt onto the surface, where they cool quickly to form small crystals.
Igneous Rocks. Igneous rocks form directly from magma inside the earth's crust (called: plutonic or intrusive) or lava on the earth's surface (volcanic or extrusive).Light-colored igneous rocks (pumice, rhyolite & granite) are composed of larger amounts of silica and are said to be felsic (feldspar + silica).gneous Rocks. Igneous rocks form directly from magma inside the earth's crust (called: plutonic or intrusive) or lava on the earth's surface (volcanic or extrusive).