Galena (mineral), mineral consisting of lead sulfide (PbS). It crystallizes in the isometric system (see Crystal), in well-formed cubes and cuboctahedrons, but it also occurs in large masses with a coarse or granular structure. Galena is characterized by perfect cubic cleavage, softness, heaviness, and the ease with which it is fused. Opaque, gray to black in color, galena has a metallic luster. Its specific gravity is 7.4 to 7.6 and its hardness 2.5 to 2.75.

Galena is an important lead and silver ore. It usually contains small amounts of silver and is often mined for the silver as well as for the lead. Smaller amounts of other metals, such as copper, gold, arsenic, antimony, and selenium, also occur in galena deposits. It is widely distributed and is frequently found associated with the sulfides of iron, copper, or zinc.