Diamonds are formed deep within the Earth's mantle under high-pressure and high-temperature conditions. The process of diamond formation, known as the diamond's "crystallization," occurs over millions of years. Here's an overview of diamond formation:
- Carbon Source: The primary component of diamonds is carbon. Carbon atoms are sourced from organic material, such as buried plant and animal remains, that undergoes metamorphism or is subducted into the Earth's mantle.
- Extreme Pressure and Temperature: Diamond formation requires specific conditions found deep within the Earth's mantle, approximately 140 to 190 kilometers (87 to 118 miles) below the surface. The pressure in this region is immense, around 725,000 to 1.13 million pounds per square inch (50,000 to 80,000 kilograms per square centimeter), and the temperature ranges from 900 to 1,300 degrees Celsius (1,650 to 2,370 degrees Fahrenheit).
- Kimberlite and Lamproite Volcanic Pipes: Diamonds are brought to the Earth's surface through explosive volcanic eruptions. These eruptions occur in vertical structures called kimberlite or lamproite pipes. These pipes act as conduits, rapidly transporting diamonds and other mantle materials to the surface.
- Rapid Cooling and Preservation: When kimberlite or lamproite magma reaches the surface, it cools rapidly, preserving the diamonds within. The rapid cooling prevents the conversion of diamond into graphite, the stable form of carbon at the Earth's surface.
- Extraction: After diamond-bearing kimberlite or lamproite pipes are identified, they are mined to extract the diamond-bearing rock. This involves various mining techniques, including open-pit mining and underground mining.
References
- Gemological Institute of America (GIA): Diamond Formation: https://www.gia.edu/diamond-formation
- American Museum of Natural History: Diamonds: Formation, Mining, and Diamond Properties: https://www.amnh.org/exhibitions/diamonds/diamonds-formation-mining-and-diamond-properties
- Geology.com: How Do Diamonds Form?: https://geology.com/articles/diamonds-from-coal/
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