Silicates

The most abundant elements in the Earth's crust are oxygen (46.6%) and silicon (27.7%). Minerals which combine these two elements are called silicates, and combined they are the most abundant minerals on the Earth. The silicates can be organized in terms of their chemical compositions and their crystal structures (indicated by the existance of cleavage planes). They most often contain members of the Big 8 elements. The table below is an example of such organization from Lutgens and Tarbuck.

Shipman, et al. comment that about 95% of the continental crust rocks are composed of the two types of feldspar or quartz.