Unlike most of the surface rocks in Kansas, which are sedimentary in origin, kimberlite is an igneous rock, formed from the cooling of molten magma.
Igneous rocks are extremely rare in Kansas.
Geologists call it an ultrabasic rock, which means it does not contain any quartz or feldspar, the two most common rock-forming minerals. Olivine, the main mineral constituent of the rock, is an olive-green, grayish green, or brown mineral made up of magnesium, iron, and silica. In 1888, the name kimberlite was proposed for this particular rock, based upon the occurrence of these rocks in the vicinity of Kimberley, South Africa. Large volumes of an olivine-rich rock type called peridotite occur at great depths in the earth in a layer called the mantle. If volatile gases, such as carbon dioxide and water, are present, they may propel the molten peridotite upwards, forming a kimberlite magma.