What does natural diamond formation require?

• A. Extreme pressures and temperatures, as well as a source of carbon
• B. Low pressure and moderate temperatures
• C. A source of silicon instead of carbon
• D. Formation in the presence of abundant water

Answer: (A)

Natural diamond formation occurs deep in the Earth's mantle where carbon is subjected to extreme pressures and high temperatures. Under these conditions, carbon atoms rearrange from graphite into the dense, rigid crystal structure of diamond. A carbon source is essential because there must be carbon atoms available to form the lattice. Low pressure and moderate temperatures won’t drive this transformation, and forming diamonds in the presence of abundant water isn’t necessary for the lattice to develop. Silicon would not produce diamond, since diamond is a form of carbon, while silicon tends to form different minerals such as silicon carbide.