The tuffs are highly calcitic, vesicular and contain numerous microxenoliths. The petrologically similar lavas show evidence of a differentiation by flow and gravity and have trachytic textures.:72, 73 Lavas have a carbonatitic composition. Olivines with diopside cores are found at the Igwisi Hills. Garnet and orthopyroxene is associated with the diopside. Olivines are surrounded by chromite. Olivines characterize the texture of the Igwisi rocks, where they form spherical inclusions. The olivines are primarily forsteritic in composition. Inclusions in the kimberlite include skeletal apatite, stellate aragonite and calcite. High concentrations of are found in the rock, which may have resulted in the depolymerization of the melt, increasing its fluidity and resulting in effusive activity. Peridotite xenoliths originate from of depth.:15 Spinels in the groundmass suggest that crustal contamination was extensive. The geochemistry suggests an origin at high pressures (depths of ) and equilibrium temperatures of . Rainfall has subsequently modified the pyroclastics and formed secondary calcite, while the less permeable lava flows were less modified.