Mons Hansteen (MH) is a Lunar volcanic complex composed of three geologic units. It was emplaced in three phases over ∼ 240 million years with oldest unit at 3.74 Ga and the youngest units at ∼ 3.5 Ga, at about the same time as the surrounding mare. It is mantled by a ∼ 9–11 m layer of pyroclastic material from the numerous vents. The close spacing of the vents in the Pitted unit may represent a new style of volcanism.