Oxygen is the most abundant element in the Earths crust, making up 46.1% of its mass. Silicon is the second most abundant element, accounting for 28.2% of the Earths crust mass. Aluminum and iron are also abundant, making up 8.2% and 5.6% of the Earths crust mass, respectively. The Earths crust comprises about 95% igneous and metamorphic rocks, 4% shale, 0.75% sandstone, and 0.25% limestone. While gold, silver, copper, and other base and precious metals are among the most sought-after elements, together they make up less than 0.03% of the Earths crust by mass.