What is the most abundant metal in the Earth's crust?

The most abundant metal in the Earth's crust is aluminum. By mass, aluminum makes up about 8.23% of the crust, making it the third-most abundant element overall after oxygen and silicon.

Aluminum is rarely found as a pure metal in nature because it bonds readily with oxygen and silicon. Instead, it is locked into minerals such as feldspars, micas, and other aluminosilicates. Bauxite, a sedimentary rock rich in aluminum minerals, is the principal ore used to produce the metal.

A common mix-up is confusing abundance with ease of extraction. Although aluminum is widespread, refining it into usable metal requires considerable energy. The Hall–Héroult process, developed independently by Charles Martin Hall and Paul Héroult in 1886, made large-scale production practical and helped turn aluminum from a precious novelty into an everyday material.

Aluminum is also much more abundant than iron in the crust, even though iron is often more visible in rocks and familiar as a structural metal. Its low density, corrosion resistance, and recyclability explain its importance in transportation, construction, packaging, and aerospace.