Kimberlite is a rough-textured igneous rock that can range from green to blue in color and typically lacks minerals common to other igneous rocks, such as quartz and feldspar. Its major component is olivine, which gives it its characteristic blue-green coloration.
Kimberlite is generally poor in the minerals most often found in igneous rocks because it forms at extreme depths. Rising from 100 to 135 miles under the surface, kimberlite magma tends to scrape other rock types from the walls of its chamber and incorporate them into its matrix. This process is responsible for its very rough, asphalt-like texture. Kimberlite samples sometimes contain garnets and diamonds, which also sets them apart from more common igneous rocks.