Rock types
Mibei (2014) classified rocks into three major types based on their formation process: the sedimentaries; the igneous; and the metamorphics. Sedimentary rocks, which comprised the majority (up to 66 percent) of Earth’s crust, formed through depositions of materials (e.g. minerals and organic particles) at the surface of or within water bodies on Earth. These rocks include limestones, sandstones, conglomerates, shales, and gypsum. Most of these rocks can be found in ocean floors and basins, which account to 70 percent of the Earth’s total land area. Igneous rocks form from magma, which solidified and cooled, including the partial ...