The complex volcanic magmas that solidify into kimberlite and lamproite are not the source of diamonds, only the elevators that bring them with other minerals and mantle rocks to Earth's surface. Although rising from much greater depths than other magmas, these pipes and volcanic cones are relatively small and rare, but they erupt in extraordinary supersonic explosions. Kimberlite and lamproite are similar mixtures of rock material. Their important constituents include fragments of rock from Earth's mantle, large crystals, and the crystallized magma that glues the mixture together. The magmas are very rich in magnesium and volatile compounds such as water and carbon dioxide.
Kimberlite magma rises through Earth's crust in networks of cracks or dikes.
The pipes only form near Earth's surface. Depth measurements show the level of erosion for various kimberlite pipes in South Africa. These drawings illustrate the formation and filling of the typical champagne-glass shape of a lamproite pipe.