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What Is a Kimberlite Pipe?

A kimberlite pipe is a rock formation that indicates a place where diamonds might be found. The very first recorded discovery of a kimberlite pipe was in diamond-rich South Africa near a city called Kimberley, and this natural volcanic phenomenon still bears the same name. Aside from being a harbinger of diamonds, kimberlite appears all over the world and is a mix of a variety of igneous rocks and minerals.

Volcanic Pipes
- Coal and diamond are both formed by volcanic activity.
  
  Diamonds form deep within the earth during volcanic activity, often 93 miles or more beneath the planet's crust. The volcanic activity that formed these rocks also carry them closer to the surface in a mixture of molten rock, minerals, rock fragments and of course, diamonds. Kimberlite pipes have tapered bases but widen as they reach the surface of the earth. The end result is a long, thin stone funnel that resembles a champagne glass.
Geology
- Volcanic magma moving beneath the earth is the beginning of kimberlite pipe.
  
  Kimberlite is a diamondiferous rock, which means that it is an igneous rock composed of many other volcanic rock and minerals like serpentine, garnet, carbonate and several other trace minerals. Deep in the earth, kimberlite pipes that are still forming form the basis for small, rare volcanoes called maars by forming dykes or volcanic pipes beneath them. Kimberlite pipes only form in a vertical shapes that stretch from the magma in the earth's crust to the surface.
Kimberlite and Diamonds
- Kimberlite pipes appear on and near the surface of the earth in many different colors. Nondiamond-bearing kimberlite is not at all rare. It is often blue or yellow and is found all over the world. Black kimberlite pipes are usually the ones that contain diamonds, but this might be unique to South Africa. The colors of kimberlite are the result of chemical explosions and extreme thermal reactions.
Mining Diamonds
- Diamonds for engagement rings must be of a high quality.
  
  Not all kimberlite pipes contain economically viable diamonds, and using colors as guidelines can be specific to the geographic area. When diamond miners find a kimberlite pipe, they have ways to evaluate it for likely diamond content. Rock is taken from the top of the pipe and processed so it can be analyzed for diamonds. These are then examined based on quality and amount to see if a mine in the area would be profitable.

Rocks & Minerals