Which Earth layer contains lithospheric diamonds, the majority of known diamonds?

• A. Crust
• B. Upper mantle
• C. Lithosphere
• D. Core

Answer: (C)

Diamonds crystallize under high pressure in the mantle, and the solid, rigid outer shell of the Earth—the lithosphere—provides the environment where many of these diamonds form and are preserved. The lithosphere includes the crust and the uppermost mantle, and it’s within this zone that kimberlite magmas originate and transport diamonds rapidly to the surface. Because this mantle-crust region is sampled most often by mining and exploration, the bulk of known diamonds comes from rocks within the lithosphere. The core lies much deeper and does not supply the diamond-bearing rocks we typically find at the surface. So the layer that contains the majority of lithospheric diamonds is the lithosphere.