Which is impure aluminum?

Impure aluminum typically refers to aluminum that contains various alloying elements or impurities, such as silicon, iron, copper, manganese, magnesium, or other metals. These impurities can be present due to the refining process or as a result of recycling. The presence of these elements can affect the physical and mechanical properties of the aluminum, influencing its strength, ductility, and corrosion resistance. Common examples of impure aluminum include aluminum scrap or lower-grade aluminum alloys used in specific applications.