During the first stage, Emi Koussi erupted trachytes and trachyandesites in the form of ignimbrites and basaltic lapilli. This was followed in the second stage by trachytic, green or grey ignimbrites, trachytic and phonolitic lava domes and additional basaltic lava flows. The second stage ignimbrites can be found within the northern caldera and on the southern flank of the volcano. The third stage was dominantly phonolitic, with breccia, tuffs and ignimbrites including the Kohor ignimbrite. The various ignimbrites contain fiamme and often look like lava flows. Each stage was accompanied by the formation of a caldera, and basaltic volcanism continued through all three stages. Phreatic explosions associated with Era Kohor have deposited large blocks within the summit caldera, including beautifully coloured syenite blocks.