As an example of the influence of just a few minerals, let’s consider the rocks of the oceanic crust. The oceanic crust is mainly composed of basalt and gabbro. These two rock types are made up of mainly of plagioclase feldspar and pyroxenes, with smaller amounts of olivine, micas and amphiboles. This small group of minerals makes up most of the rocks of the oceanic crust.
Rock-Forming Minerals in Major Rock Types: This chart shows the relative abundance of the common rock forming minerals in some of Earth’s most abundant rock types. Basalt and gabbro account for most of the rock in the oceanic crust, granite (rhyolite) and andesite (diorite) represent abundant rock types of the continental crust. Sandstone, shale and carbonates represent the common materials in the sedimentary cover of continents and ocean basins.
