Uniquely for volcanoes on Earth, it has erupted natrocarbonatite,[2] an unusually low temperature and highly fluid type of magma.

[9] Ol Doinyo Lengai is a symmetric cone[1] that rises more than 1,800 metres (5,900 ft) above the surrounding rift valley.

[14] White volcanic ash deposits cover the slopes of the volcano,[11] which have large fractures on the western flank.

[22] The Natron Fault, the western boundary of the Gregory Rift in the area, passes just southwest of the volcano.

[21] Chemical composition: The carbonatite lavas are rapidly chemically modified by rainfall[30] or covered by deposits condensing from fumarolic gases,[31] yielding secondary minerals like calcite, gaylussite, nahcolite, pirssonite, shortite, thermonatrite, and trona,[32] including various chlorides, fluorides,[f] and sulfates.

[36] There appear to be two magma reservoirs under the volcano,[37] and its plumbing system is complex, involving regional tectonic structures.

[38] Volcanic gas sampled at Ol Doinyo Lengai consists mostly of water vapor and carbon dioxide and originates in the mantle.

[26] Radiometric dates obtained by geologists for the start of volcanic eruptions at Ol Doinyo Lengai range from more than 500,000 to 22,000 years ago.

[26] The emission of a lava flow onto the western flank of Ol Doinyo Lengai in 2006 was accompanied by the formation of a pit crater on the summit.

[54] The explosive activity continued into 2008, when the volcano settled back into the effusion of lava flows;[53] a cinder cone formed in the northern crater during the eruption.

[57] The 2007 eruptions forced the evacuation of three villages[58] and disturbed air travel in the touristically important area;[59] livestock fatalities and injuries to people led to requests that the government of Tanzania enact access restrictions to the volcano[60] and to increased awareness of the threat formed by the volcano.

[38] Lavas erupted by Ol Doinyo Lengai initially have brown or black colors, but within days[45] to hours become white like snow.

[11] The lavas of Ol Doinyo Lengai have temperatures of 540–593 °C (1,004–1,099 °F);[5] they are so cold that during the day they look like mudflows[i] or oil and glow only during the night.

[9] Volcanic ash from Ol Doinyo Lengai influences the surrounding landscape, favoring the growth of nutrient-rich plants.