Key Terms

Carbonado—An aggregate of many randomly oriented interlocking tiny diamond crystals that is the toughest form of diamond.

Carbonate—A class of chemical compounds that contain carbon and oxygen.

CLIPPIR Diamonds—Cullinan-like, Large, Inclusion-Poor, Pure, Irregular, and Resorbed diamond.

Core—The earth’s innermost layer.

Cratons—Large, ancient, stable parts of the earth’s landmasses.

Crust—The surface and outermost layer of the earth.

Crustal Diamond—Rare diamond that forms in the continental crust at or near the earth’s surface due to meteorite impact or tectonic plate collision.

Eruption—A geological process that delivers material (sometimes diamonds) to the surface.

Geothermal Gradient—The rate of temperature increase with depth in the earth.

Igneous Rock—A type of rock formed from a molten state.

Lithosphere—The layer that contains the crust and the uppermost part of the mantle.

Magma—Any molten rock within the earth.

Mantle—The layer between the earth's crust and its core.

Mantle Keels—A large, downward-protruding portion of the lithosphere under a craton.

Metamorphic Rock—A type of rock that has been altered by heat and pressure.

Metasomatism—A process in which chemical changes in minerals and rocks result from the introduction of material from external sources, often fluids or melts.

Mineral—A natural, inorganic substance with characteristic chemical composition and usually characteristic structure.

Pipe—A deep vertical formation at the earth’s surface that results from a kimberlite or lamproite eruption.

Plate Tectonics—The theory of the formation, structure, and movement of the earth’s landmasses.

Rocks—A natural material composed of one or more kinds of minerals.

Subduction—The process in which a continental plate and an oceanic plate collide, forcing the oceanic plate down into the mantle.

Superdeep Diamonds—Diamonds that formed at 410 km or deeper beneath the earth’s surface.

Transition Zone—The layer between the upper and lower mantles.