Sulfur, salt, and other minerals color the crater of Dallol. The colorful springs on Dallol mountain derive their colors mainly from ferrous chloride and iron hydroxide (both white-greenish), ferric chloride (yellow-brown) and iron oxide (brown).
Dallol is nested on top of an at least 1000m thick layer of quaternary evaporates including large potash (potassium salt) reserves.
Currently, activity is in the form of hot brine springs. Salts washed out of the underlying layers are transported to the surface by geothermally heated water and rapidly crystallize as the water evaporates. The characteristic white, yellow and red colors are the result of sulfur and potassium salts colored by various ions.