The Earth’s crust is the outermost solid layer of the Earth, comprising all three types of rocks: igneous, sedimentary, and metamorphic rocks. Igneous rocks constitute the largest portion of the Earth’s crust, accounting for 90-95% of the total volume, formed as a result of the cooling of magma or lava. Metamorphic rocks constitute a large portion of the remaining crust, formed as a result of the transformation of existing rocks due to high pressure and temperatures. Sedimentary rocks form a thin layer, covering 73-75% of the Earth’s land surface, but only 5-8% of the total volume of the Earth’s crust.