ASS #3 Key Terms & Concepts PDF

ASS #3 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, Irregu...

ASS #3 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. Key Concepts *Diamond and graphite are both composed of carbon. *The earth’s basic structure consists of the crust, mantle, and core. *The mantle can be divided into three broad layers: the upper mantle, lower mantle, and a transition zone in between. *Mantle convection drives the movement of the earth’s plates. *Subduction is an essential part of diamond formation. *Most diamond deposits are found on cratons or in the areas surrounding them. *Diamonds form mainly in two types of rocks: peridotite and eclogite. *Diamond formation requires extreme pressures and temperatures, as well as a source of carbon. *The conditions for diamond formation exist within mantle keels under cratons. *The majority of mined diamonds are lithospheric and superdeep. * Not all diamonds form in mantle keels; superdeep diamonds form much deeper within the mantle. *Diamonds form in mantle keels when carbon is available and free to bond with other carbon atoms without oxygen. *Inclusions can indicate where a diamond formed within the earth. *CLIPPIR diamonds crystallized from metallic melts in the transition zone or the lower mantle. *The most common cause of blue color in diamonds is boron. *Boron in blue diamonds originates from oceanic plates. *Carbonado is the toughest form of diamond. *Diamonds were delivered to the surface between 2.5 billion and 20 million years ago. *Kimberlite and lamproite are the two igneous rocks that transport diamonds to the surface. *Diamond-bearing kimberlite is much more common than diamond-bearing lamproite. *Kimberlite tends to occur in the center of cratons, while lamproite occurs at their edges. *Kimberlite and lamproite form pipe deposits. *Very few kimberlites or lamproites contain diamonds in economic quantities.