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Diamond

Diamond

Composed of pure carbon, diamonds are the hardest known material. Because of this they are indispensable to industry. Diamonds are also valuable to geologists, who learn from them about the conditions in the interior of the earth. To a geologist, diamonds are reminders of the tremendous temperatures and pressures within our dynamic planet. Only about one-third of diamonds found are big enough to be cut into gems.

Diamond (in conglomerate)

Diamond (in conglomerate)

Diamonds hitch a ride to the surface in rare magmas called kimberlite and lamproite, which form by partial melting of the upper mantle. Gas expansion propels these magmas upward at rates of 10-30 kph (6-19 mph), giving their diamond passengers a commute time of just 4-15 hours from mantle to surface! At the surface water can transport the diamonds and other particles away from the point of eruption, leaving the diamond embedded in sedimentary rocks, like this conglomerate.

Diamond (in Eclogite)

Diamond (in Eclogite)

Diamonds grow at depths of at least 150 km (90 mi), in the thick lithosphere beneath the older parts of continents. By comparing the different kinds of carbon atoms in diamonds, scientists can track the carbon's source. Some carbon was once organic matter on Earth's surface and was subducted into the mantle. The rest originated in the mantle.

Diamond (in Garnet)

Diamond (in Garnet)

Diamonds grow at depths of at least 150 km (90 mi), in the thick lithosphere beneath the older parts of continents. By comparing the different kinds of carbon atoms in diamonds, scientists can track the carbon's source. Some carbon was once organic matter on Earth's surface and was subducted into the mantle. The rest originated in the mantle.

Diamond Crystal (in Kimberlite)

Diamond Crystal (in Kimberlite)

Composed of pure carbon, diamonds are the hardest known material. Because of this they are indispensable to industry. Diamonds are also valuable to geologists, who learn from them about the conditions in the interior of the earth. Only about one-third of diamonds found are big enough to be cut into gems.


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