Ol Donyo Lengai (maasai: mountain of god) is a revered and active volcano in northern Tanzania. It is the only volcano in the world to erupt lava that contains certain rare carbonate minerals and this confers it unique characteristics. One of these is the temperature of the lava which, at 510°C, is considerably cooler that the approximate 1100°C lava of basaltic volcanoes.
The summiting of Lengai (2886m/9524ft) was a fantastic experience. While it is just 200km from Arusha, it is an adventure to get to the base camp beside Lake Natron as the later stages of the journey are through trackless savannah punctuated with huge pits of bull dust. Lengai has been in a constant state of eruption since September 2007 and many would advise caution if considering an ascent. Despite being cooler than basaltic lava, it is far less viscose and I can attest to the fact that it behaves like water when it flows or is projected through the air towards you!