Ol Doinyo Lengai is the only active volcano in the world that erupts natrocarbonatite lava, an exceptionally rare type of lava that is rich in sodium and potassium carbonate minerals. Unlike typical basaltic lava, this lava is cooler (approximately 500–600°C), highly fluid, and appears black when molten, but it quickly turns white upon exposure to air due to rapid weathering. This distinctive characteristic has earned the mountain the nickname “The White Volcano.”

The eruptions of Ol Doinyo Lengai are frequent but typically not explosive, with most activity consisting of effusive lava flows and small Strombolian eruptions. The last major eruptions occurred in 2007–2008, altering the shape of the crater and surrounding landscape.