The coldest erupting lava in the world is the natrocarbonatite lava of the volcano Oldoinyo Lengai, Tanzania that erupts at temperatures of 500-600°C (930-1,110 °F). Common basaltic lavas erupt at temperatures between 1,100 and 1,200°C (2,010-2,190 °F).
Oldoinyo Lengai is the only active carbonatite volcano on Earth. The bizarre carbonatite lavas look rather like molten chocolate upon eruption. It is extremely runny and has the lowest viscosity of any lava. Upon cooling it turns white in colour.