To determine which metal has an FCC crystal structure, we recall common crystal structures of elemental metals. Alpha iron (\(\alpha\)-Fe) has a body-centered cubic (BCC) structure at room temperature. Chromium is also BCC. Magnesium possesses a hexagonal close-packed (HCP) structure. Aluminum, however, crystallizes in a face-centered cubic (FCC) lattice, which gives it excellent ductility and formability. Therefore, the correct option is Aluminum.
Final Answer: Aluminum