Diamonds form at depths of about how many kilometers beneath the surface?

Diamonds form at depths of about how many kilometers beneath the surface?

• A. 50-100 km
• B. 100-140 km
• C. 140-220 km
• D. 220-300 km

Answer: (C)

Diamonds form under the very high-pressure conditions found in the Earth's mantle, where carbon can crystallize into the diamond structure rather than graphite. That diamond stability field sits roughly around 140 to 220 kilometers below the surface, where pressures are on the order of several gigapascals. Kimberlite magmas transport diamonds from these depths up to the surface, which is why this depth range is used to describe where natural diamonds form. The shallower ranges don’t reach the necessary pressures for diamond formation, while the deeper option isn’t the typical formation depth associated with most natural diamonds. So the best-fit range is about 140–220 kilometers.

Diamonds form under the very high-pressure conditions found in the Earth's mantle, where carbon can crystallize into the diamond structure rather than graphite. That diamond stability field sits roughly around 140 to 220 kilometers below the surface, where pressures are on the order of several gigapascals. Kimberlite magmas transport diamonds from these depths up to the surface, which is why this depth range is used to describe where natural diamonds form. The shallower ranges don’t reach the necessary pressures for diamond formation, while the deeper option isn’t the typical formation depth associated with most natural diamonds. So the best-fit range is about 140–220 kilometers.