(above) atoms arranged in a cubic close packing pattern
METALLIC STRUCTURE: the atoms in metals are arranged in several ways. Generally, they pack together very tightly. The variant shown here is called cubic close packing (the other close packing variant is called hexagonal close packing). In CCP, the metal atoms are arranged in closely packed hexagonal layers and first and fourth layers are in line with each other (top and bottom atomic layers in this image). The translucent purple volume illustrates cube (rotated in relation to the hexagonal strata). Each face of the cube has an atom in the middle (hence the alternate name of face centred cubic close packing). The atoms in this purple box all belong to a unit cell (illustrated as a dark pink solid structure whose vertices lie at the centres of the atoms mentioned). A vast array of such unit cells makes up the crystal of the metal.
Image is 500 pixels across, the originals are 4096 pixels across.