Taxonomy term

diamond

Diamonds and the Eocene climate of the Bell River Basin

Diamonds mined from the kimberlite pipes of the Lac de Gras diamond field in Northwest Territories, Canada, are among the world’s youngest known diamonds, dating from 75 million to 45 million years ago. In some cases, when the magmas that carried these diamonds to Earth’s surface encountered water-saturated rock at shallow depths, violent steam explosions called phreatomagmatic eruptions resulted. Such explosions can form volcanic craters known as maars, which often fill with water and accumulate lake sediment, along with soil and vegetation that collapse into them from their margins. In the case of the Panda kimberlite pipe at the Ekati Mine in the Lac de Gras area, maar sediments accumulated far below the surrounding terrain, such that they were later buried under glacial deposits rather than being eroded away by ice sheets during the past million years. Wood and other organic materials were entombed and preserved in their natural state, thereby preserving shreds of the Paleo-Bell River Basin.

25 Jul 2018

Diamonds reveal water in deep mantle

Inclusions in diamonds often render them undesirable to consumers, but they can provide researchers with striking insights into Earth’s composition. Recently, scientists probing diamond samples for the presence of carbon dioxide stumbled instead upon inclusions of ice-VII — a type of crystallized water that forms at very high pressures, and has never before been found in nature.

07 Jul 2018

Junk gem reveals new diamond-forming process

Not all diamonds are gems. Those found bearing imperfections or inclusions, known as bort or junk diamonds, are often demoted to industrial uses such as in diamond-tipped drill bits. They also sometimes find their way to scientists interested in using the inclusions to study how such stones form. Now, a team studying a junk diamond from Botswana with a large black sulfide inclusion has uncovered evidence of a previously unrecognized diamond formation process that occurs in the deep mantle.

 
16 Sep 2016

Subducted seawater the source of fluid-rich diamonds

Subducting oceanic plates that dive hundreds of kilometers beneath Earth’s surface carry with them cargoes of sediment and seawater. As the plate heats up the deeper it sinks, this seawater not only initiates melting in the rock above it, but can also trigger diamond formation, suggest the authors of a new study in Nature.

30 Sep 2015

Thorny plant marks West African diamond deposits

West Africa is famous for diamonds, brought up from the depths of Earth’s mantle eons ago during explosive volcanic eruptions. On the surface, the eroded remains of these eruptions, known as kimberlite pipes, are infamously hard to find under the thick jungles of Guinea, Sierra Leone and Liberia, and only a few of the deep, narrow pipes contain profitable diamonds. Now, a researcher has identified an unusual feature that might point the way toward such pipes, and possibly revolutionize the search for diamond-rich deposits: a tall, thorny palm-like plant that seems to only grow atop kimberlites.
 
23 Aug 2015

A watery surprise from Earth's depths: Mineral provides first direct evidence for water in mantle's transition zone

From a depth of more than 500 kilometers, Earth has coughed up a water-bearing mantle mineral never before found on the surface. The surprise finding suggests the planet’s interior holds more water than all its oceans combined, and could help explain how Earth’s massive tectonic plates move.

14 Jul 2014

January 26, 1905: The world's largest gem-quality diamond is unearthed

Each day, thousands of visitors to the Smithsonian Institution's National Museum of Natural History view the rare and spectacular Hope Diamond, a 45-carat blue diamond. And dozens of diamonds bigger than the Hope — with names like Excelsior, Incomparable and Jubilee — have also been retrieved, cut and polished to perfection.

26 Jan 2014

Travels in Geology: Arkansas: A geologic diamond in the rough

If the budget belt is a little tighter this year, consider packing your diamond-digging trowel, bathing suit and camping gear and heading to a little-known geologic hot spot in the middle of the United States. Arkansas, “the Natural State,” boasts the world’s only public diamond mine, uniquely heated mineral springs and the Ozark Mountains of Wilson Rawls’ “Where the Red Fern Grows” lore, all within a day’s drive from much of the United States.

10 Sep 2009

November 26,1872: Great Diamond Hoax Exposed

By Cassandra Willyard

On a foggy day in 1871, two men walked into the Bank of California in San Francisco. One held a rifle and the other gripped a large buckskin pouch. Both were covered in a thick layer of grime. Initially, the nervous teller took the shady drifters for bank robbers. But his anxiety turned to elation when they showed him the contents of their pouch — a shimmery bounty of diamonds, rubies and sapphires.

26 Nov 2008