How Do Slow Anomalies Beneath Subducting Slabs Affect Giant Megathrust Earthquakes?

<p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-OZ9SbQEoxEo/YIoh7qtgB5I/AAAAAAAAS9c/5DCEGzN4viU1EYu46CKk09BKBoaddIeiwCLcBGAsYHQ/s1092/how-do-slow-anomalies-.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="764" data-original-width="1092" height="448" src="https://1.bp.blogspot.com/-OZ9SbQEoxEo/YIoh7qtgB5I/AAAAAAAAS9c/5DCEGzN4viU1EYu46CKk09BKBoaddIeiwCLcBGAsYHQ/w640-h448/how-do-slow-anomalies-.jpg" title="How Do Slow Anomalies Beneath Subducting Slabs Affect Giant Megathrust Earthquakes?" width="640" /></a></div> <br /><p></p><p> </p><p>Earthquakes and volcanoes in subduction zones may cause great human catastrophe. Previous studies on subduction zone structure and causal mechanisms of giant megathrust earthquakes (M ≥ 9.0) have mainly focused on aspects like subducting plates and plate interfaces.<br /><br />In contrast, the oceanic asthenosphere structure beneath the subducting slab (at depths of 100-250 km) and its influence on the nucleation of giant megathrust earthquakes have not been well studied.<br /><br />Recently, Dr. Fan Jianke from the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS) and Prof. Zhao Dapeng from Tohoku University turned their attention to this problem by investigating the oceanic asthenosphere structure of six subduction zones where giant earthquakes have occurred.<br /><br />The researchers adopted P-wave tomographic inversions and compiled updated tomographic models. The tomographic images clearly reveal subslab low-velocity (slow) anomalies beneath forearc regions in the six subduction zones.<br /><br />"The giant earthquake hypocenters are generally located above the edges of the slow anomalies or above the gaps between them. Large coseismic slips of the giant earthquakes mainly occur above gaps between the slow anomalies," said Dr. Fan.<br /><br />The buoyancy force of a subslab slow anomaly can increase interplate shear stress by enhancing interplate normal stress. Interplate shear stress increases the critical stress threshold for rupture, and the critical shear stress above the slow anomaly gap is slightly smaller than that above the slow anomaly.<br /><br />However, critical shear stress is still large enough and relatively easier to reach. As such, it can induce a giant megathrust earthquake above the slow anomaly gap, which is primarily controlled by structural heterogeneity on and around the plate interface.<br /><br />In addition, the buoyancy force of the slow anomaly can cause a morphological response from the subducting slab, thus increasing the shear stress on the plate interface. Thermal conduction or thermo-mechanical erosion from the slow anomaly may result in transformation of the interface rheology from frictional to viscous shear.<br /><br />This transformation may partly account for the occurrence of slow-slip earthquakes above slow anomalies. The slow-slip area can impede rupture propagation and host afterslip of a giant megathrust earthquake.<br /><br />"It's necessary to conduct seismic tomography to investigate more detailed asthenospheric structures beneath a subducting slab, which may pinpoint the potential location of a future giant megathrust earthquake," said Dr. Fan.</p><p><br /><i><u>The above story is based on <a href="https://www.nature.com/articles/s41561-021-00728-x" rel="nofollow" target="_blank">materials </a>provided by<a href="https://english.cas.cn/" rel="nofollow" target="_blank"> Chinese Academy of Sciences.</a></u></i><br /> <br /></p>

How Do Slow Anomalies Beneath Subducting Slabs Affect Giant Megathrust Earthquakes?

    Earthquakes and volcanoes in subduction zones may cause great human catastrophe. Previous studies on subduction zone structure and causa...

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Earth’s Continental Crust Emerged 500 Million Years Earlier Than Thought

<p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-jqtA4AaiE0U/YIdqNQc7aWI/AAAAAAAAS9Q/H4Yev3TjH3QW0AJJpQOZD0Z9wzymtkC4gCLcBGAsYHQ/s1145/Earth%25E2%2580%2599s%2BContinental%2BCrust%2BEmerged%2B500%2BMillion%2BYears%2BEarlier%2BThan%2BThought%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="688" data-original-width="1145" height="384" src="https://1.bp.blogspot.com/-jqtA4AaiE0U/YIdqNQc7aWI/AAAAAAAAS9Q/H4Yev3TjH3QW0AJJpQOZD0Z9wzymtkC4gCLcBGAsYHQ/w640-h384/Earth%25E2%2580%2599s%2BContinental%2BCrust%2BEmerged%2B500%2BMillion%2BYears%2BEarlier%2BThan%2BThought%2B%25281%2529.jpg" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">An artist’s conception of the early Earth, showing a surface bombarded by large impacts that result in the extrusion of magma onto the surface. At the same time, distal portions of the planet’s surface may have retained liquid water. Credit: Simone Marchi/SwRI</td></tr></tbody></table> </p><p>The first emergence and persistence of continental crust on Earth during the Archaean (4 billion to 2.5 billion years ago) has important implications for plate tectonics, ocean chemistry, and biological evolution, and it happened about half a billion years earlier than previously thought, according to new research being presented at the EGU General Assembly.<br /><br />Once land becomes established through dynamic processes like plate tectonics, it begins to weather and add crucial minerals and nutrients to the ocean. A record of these nutrients is preserved in the ancient rock record. Previous research used strontium isotopes in marine carbonates, but these rocks are usually scarce or altered in rocks older than 3 billion years.<br /><br />Now, researchers are presenting a new approach to trace the first emergence of old rocks using a different mineral: "barite."<br /><br />Barite forms from a combination of sulfate coming from ocean water mixing with barium from hydrothermal vents. Barite holds a robust record of ocean chemistry within its structure, useful for reconstructing ancient environments. "The composition of the piece of barite we pick up in the field now that has been on Earth for three and a half billion years, is exactly the same as it was when it when it actually precipitated," says Desiree Roerdink, a geochemist at University of Bergen, Norway, and team leader of the new research. "So in essence, it is really a great recorder to look at processes on the early Earth."<br /><br />Roerdink and her team tested six different deposits on three different continents, ranging from about 3.2 billion to 3.5 billion years old. They calculated the ratio of strontium isotopes in the barite, and from there, inferred the time where the weathered continental rock made its way to the ocean and incorporated itself into the barite. Based on the data captured in the barite, they found that weathering started about 3.7 billion years ago -- about 500 million years earlier than previously thought.<br /><br />"That is a huge time period," Roerdink says. "It essentially has implications for the way that we think about how life evolved." She added that scientists usually think about life starting in deep sea, hydrothermal settings, but the biosphere is complex. "We don't really know if it is possible that life could have developed at the same time on land," she noted, adding "but then that land has to be there."<br /><br />Lastly, the emergence of land says something about plate tectonics and the early emergence of a geodynamic Earth. "To get land, you need processes operating to form that continental crust, and form a crust that is chemically different from the oceanic crust," Roerdink says.</p><p> </p><p><i><u><span style="font-family: trebuchet;">The above story is based on <a href="https://www.egu.eu/news/843/new-research-uncovers-continental-crust-emerged-500-million-years-earlier-than-previously-thought/" rel="nofollow" style="-webkit-text-stroke-width: 0px; background-color: white; border-radius: 0px !important; box-sizing: border-box; color: #004276; font-size: 14px; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;" target="_blank">Materials</a><span style="-webkit-text-stroke-width: 0px; background-color: white; color: #333333; display: inline !important; float: none; font-size: 14px; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><span> </span>provided by<span> </span></span><a href="http://www.egu.eu/" rel="nofollow" style="-webkit-text-stroke-width: 0px; background-color: white; border-radius: 0px !important; box-sizing: border-box; color: #004276; font-size: 14px; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;" target="_blank"><strong style="border-radius: 0px !important; box-sizing: border-box; font-weight: bold;">European Geosciences Union</strong></a><span style="-webkit-text-stroke-width: 0px; background-color: white; color: #333333; display: inline !important; float: none; font-size: 14px; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">.</span></span></u></i> </p>

Earth’s Continental Crust Emerged 500 Million Years Earlier Than Thought

An artist’s conception of the early Earth, showing a surface bombarded by large impacts that result in the extrusion of magma onto the surfa...

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Mysterious Melting of Earth’s Crust in Western North America Investigated by Scientists

<p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-lD_eSxp9z2o/YIOGLdUKwNI/AAAAAAAAS9I/a3U5QuZP-BMgAaCDR0vhUMc4eIG7ksQKgCLcBGAsYHQ/s1202/Mysterious%2BMelting%2Bof%2BEarth%25E2%2580%2599s%2BCrust%2Bin%2BWestern%2BNorth%2BAmerica%2BInvestigated%2Bby%2BScientists%2B%25281%2529.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="768" data-original-width="1202" height="408" src="https://1.bp.blogspot.com/-lD_eSxp9z2o/YIOGLdUKwNI/AAAAAAAAS9I/a3U5QuZP-BMgAaCDR0vhUMc4eIG7ksQKgCLcBGAsYHQ/w640-h408/Mysterious%2BMelting%2Bof%2BEarth%25E2%2580%2599s%2BCrust%2Bin%2BWestern%2BNorth%2BAmerica%2BInvestigated%2Bby%2BScientists%2B%25281%2529.jpg" width="640" /></a></div> <br /><p></p><p>A group of University of Wyoming professors and students has identified an unusual belt of igneous rocks that stretches for over 2,000 miles from British Columbia, Canada, to Sonora, Mexico.<br /><br />The rock belt runs through Idaho, Montana, Nevada, southeast California and Arizona.<br /><br />“Geoscientists usually associate long belts of igneous rocks with chains of volcanoes at subduction zones, like Mount Shasta, Mount Hood, Mount St. Helens and Mount Rainer,” says Jay Chapman, an assistant professor in UW’s Department of Geology and Geophysics. “What makes this finding so interesting and mysterious is that this belt of igneous rocks is located much farther inland, away from the edge of the continent, and doesn’t contain any evidence for producing volcanoes. In fact, all of the melting to generate the igneous rocks originally took place deep underground, five to 10 miles beneath the surface.”<br /><br />Chapman is lead author of a paper, titled “The North American Cordilleran Anatectic Belt,” which was published online in February in the journal Earth-Science Reviews. The print version will be published this month.<br /><br />The paper is a result of a special course taught by Simone Runyon, an assistant professor in UW’s Department of Geology and Geophysics, and Chapman. Runyon, six UW graduate students and one undergraduate student, who took part in the course, are co-authors of the paper.<br /><br />“It was really fascinating to start with a scientific question in a classroom, then collect and analyze data, and eventually publish our results,” says Cody Pridmore, a UW graduate student from Orange, Calif., and co-author of the paper. “It’s a process most college students don’t get to experience.”<br /><br />One clue to the origin of the belt of igneous rocks is that the rocks chiefly formed 80 million to 50 million years ago, during a mountain-building event called the Laramide orogeny.<br /><br />“The Laramide orogeny created most of the major mountain ranges we have in Wyoming, and the name actually comes from the Laramie Range,” Chapman says. “Although there are no igneous rocks of this type and age present in those mountains, we suspect that the tectonic processes that created the mountains also contributed to melting Earth’s crust.”<br /><br />The researchers have several working hypotheses about what caused the rocks to melt. One hypothesis is that water infiltrated the deep crust.<br /><br />“The geochemistry of these rocks indicates that melting may have occurred at relatively low temperatures, below 800 degrees Celsius,” says Jessie Shields, a Ph.D. student at UW from Minneapolis, Minn., who is working to solve this mystery. “That is still very hot, but not hot enough to produce very large volumes of magma. Water lowers the melting point of rocks, similar to how salt lowers the melting point of ice, and could increase the amount of magma generated.”<br /><br />This work has implications for what causes rocks to melt and where specific types of magmas can be found.<br /><br />“Many of the igneous systems in the study area contain economically important ore deposits,” says Runyon, who specializes in ore deposits. “Understanding the large-scale igneous processes that form these provinces helps us to better understand how ore deposits form and to better explore for natural resources.”<br /><br />The research project is a joint effort involving UW; Andy Barth, a professor at Indiana University-Purdue University Indianapolis; and Gordon Haxel, a U.S. Geological Survey scientist based in Flagstaff, Ariz. Other UW students involved were graduate students Brandi Lawler, of Gordon, Wisc.; Shane Scoggin, of Reston, Va.; Nathan Swaim, of Monument, Colo.; and Adam Trzinski, of Manteno, Ill.; and undergraduate Hannah Wiley, of Sheridan.</p><p> <br /><i><u>The above story is based on <a href="http://www.uwyo.edu/uw/news/2021/04/uw-scientists-probe-mysterious-melting-of-earths-crust-in-western-north-america.html" rel="nofollow" target="_blank">materials </a>provided by <a href="http://www.uwyo.edu/" rel="nofollow" target="_blank">University of Wyoming.</a></u></i><br /></p>

Mysterious Melting of Earth’s Crust in Western North America Investigated by Scientists

  A group of University of Wyoming professors and students has identified an unusual belt of igneous rocks that stretches for over 2,000 mil...

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The Colorful Charm of Ametrine

<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-OdR3RfcAKxI/YHV65_Z2WBI/AAAAAAAAS8c/8FfaoPO3b_4yL6zYCxpAIzksAOeVujC4QCLcBGAsYHQ/s1272/7511cdce7c41df3916a7a1edd7ed1768.jpg" style="margin-left: auto; margin-right: auto;"><img alt="The Colorful Charm of Ametrine" border="0" data-original-height="824" data-original-width="1272" height="414" src="https://1.bp.blogspot.com/-OdR3RfcAKxI/YHV65_Z2WBI/AAAAAAAAS8c/8FfaoPO3b_4yL6zYCxpAIzksAOeVujC4QCLcBGAsYHQ/w640-h414/7511cdce7c41df3916a7a1edd7ed1768.jpg" title="The Colorful Charm of Ametrine" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The Colorful Charm of Ametrine.  Rough Ametrine. Credit: GoldenHourMinerals<br /></td></tr></tbody></table><br /><p>A bicolor variety of quartz that is purple amethyst on one side and orange citrine on the other, ametrine occurs naturally only at the Anahí Mine in the Sandoval Province of eastern Bolivia.<br /><br />Ametrine is composed of silicon dioxide (SiO₂ ) and it is a tectosilicate, which means it has a silicate framework linked together through shared oxygen atoms.<br /><br />Ametrine is a mix of both Ametrine and Citrine producing a mixture of purple and yellow/orange crystal colours. It is produced under such exceptional and improbable conditions, requiring a perfect combination of iron presence and differing temperatures within a very confined area, that it has occurred only once that we know of, in only one known place in the world: Santa Cruz, Bolivia. </p><p>The Anahí mine is the one and only bolivianite mine known to exist anywhere on Earth. The mineralization is found in the northern part of a hill formed by limestones and dolomites, and has been generated by silicification of the limestones belonging to the Murcielago Group, deposited in the Precambrian, between 500 and 900 million years ago. Ametrine crystals are found in hydrothermal breccias.<br /><br />The Anahi ametrine crystals range in size from 10 to 30 cm in length and 4 to 12 cm in diameter. When sliced and polished, the interior of the crystals show the typical color zoning. The amethyst and citrine zones run from top to bottom, parallel to the crystal’s c-axis.<br /><br />Ametrine in the low price segment may stem from synthetic material. Green-yellow or golden-blue ametrine does not exist naturally. This gem only exists in Bolivia, it comes from the Ricón del Tigre area, from the Anahí mine.<br /><br /></p>

The Colorful Charm of Ametrine

The Colorful Charm of Ametrine.  Rough Ametrine. Credit: GoldenHourMinerals A bicolor variety of quartz that is purple amethyst on one side ...

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How Could Surface Minerals Get in Diamonds Found in The Deepest Depths of The Earth?

<p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-3yFwtU27r-Y/YG3m8Q4g4KI/AAAAAAAAS8M/NiClbK81YwMWjjb7p91rk0pQg3up4XkLACLcBGAsYHQ/s1280/diamond_with_inclusion%2B%25281%2529.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="842" data-original-width="1280" height="420" src="https://1.bp.blogspot.com/-3yFwtU27r-Y/YG3m8Q4g4KI/AAAAAAAAS8M/NiClbK81YwMWjjb7p91rk0pQg3up4XkLACLcBGAsYHQ/w640-h420/diamond_with_inclusion%2B%25281%2529.jpg" width="640" /></a></div> <br /><p></p><p><span style="font-family: georgia;">Diamonds that formed hundreds of kilometers deep below Earth's surface contain traces of chemical reactions that took place on the bottom of the ocean.</span><br /></p><p>Diamonds that formed deep in the Earth's mantle contain evidence of chemical reactions that occurred on the seafloor. Probing these gems can help geoscientists understand how material is exchanged between the planet's surface and its depths.<br /><br />New work published in Science Advances confirms that serpentinite -- a rock that forms from peridotite, the main rock type in Earth's mantle, when water penetrates cracks in the ocean floor -- can carry surface water as far as 700 kilometers deep by plate tectonic processes.<br /><br />"Nearly all tectonic plates that make up the seafloor eventually bend and slide down into the mantle -- a process called subduction, which has the potential to recycle surface materials, such as water, into the Earth," explained Carnegie's Peng Ni, who co-led the research effort with Evan Smith of the Gemological Institute of America.<br /><br />Serpentinite residing inside subducting plates may be one of the most significant, yet poorly known, geochemical pathways by which surface materials are captured and conveyed into the Earth's depths. The presence of deeply-subducted serpentinites was previously suspected -- due to Carnegie and GIA research about the origin of blue diamonds and to the chemical composition of erupted mantle material that makes up mid-ocean ridges, seamounts, and ocean islands. But evidence demonstrating this pathway had not been fully confirmed until now.<br /><br />The research team -- which also included Carnegie's Steven Shirey, and Anat Shahar, as well as GIA's Wuyi Wang and Stephen Richardson of the University of Cape Town -- found physical evidence to confirm this suspicion by studying a type of large diamonds that originate deep inside the planet.<br /><br />"Some of the most famous diamonds in the world fall into this special category of relatively large and pure gem diamonds, such as the world-famous Cullinan," Smith said. "They form between 360 and 750 kilometers down, at least as deep as the transition zone between the upper and lower mantle."<br /><br />Sometimes they contain inclusions of tiny minerals trapped during diamond crystallization that provide a glimpse into what is happening at these extreme depths.<br /><br />"Studying small samples of minerals formed during deep diamond crystallization can teach us so much about the composition and dynamics of the mantle, because diamond protects the minerals from additional changes on their path to the surface," Shirey explained.<br /><br />In this instance, the researchers were able to analyze the isotopic composition of iron in the metallic inclusions. Like other elements, iron can have different numbers of neutrons in its nucleus, which gives rise to iron atoms of slightly different mass, or different "isotopes" of iron. Measuring the ratios of "heavy" and "light" iron isotopes gives scientists a sort of fingerprint of the iron.<br /><br />The diamond inclusions studied by the team had a higher ratio of heavy to light iron isotopes than typically found in most mantle minerals. This indicates that they probably didn't originate from deep-Earth geochemical processes. Instead, it points to magnetite and other iron-rich minerals formed when oceanic plate peridotite transformed to serpentinite on the seafloor. This hydrated rock was eventually subducted hundreds of kilometers down into the mantle transition zone, where these particular diamonds crystallized.<br /><br />"Our findings confirm a long-suspected pathway for deep-Earth recycling, allowing us to trace how minerals from the surface are drawn down into the mantle and create variability in its composition," Shahar concluded.</p><p> </p><p><span style="font-family: times;"><i><u>The above story is based on <a href="https://carnegiescience.edu/news/deep-diamonds-contain-evidence-deep-earth-recycling-processes" rel="nofollow" style="-webkit-text-stroke-width: 0px; background-color: white; border-radius: 0px !important; box-sizing: border-box; color: #004276; font-size: 14px; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;" target="_blank">Materials</a><span style="-webkit-text-stroke-width: 0px; background-color: white; color: #333333; display: inline !important; float: none; font-size: 14px; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><span> </span>provided by<span> </span></span><a href="https://carnegiescience.edu/" rel="nofollow" style="-webkit-text-stroke-width: 0px; background-color: white; border-radius: 0px !important; box-sizing: border-box; color: #004276; font-size: 14px; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;" target="_blank"><strong style="border-radius: 0px !important; box-sizing: border-box; font-weight: bold;">Carnegie Institution for Science</strong></a></u></i></span><span style="-webkit-text-stroke-width: 0px; background-color: white; color: #333333; display: inline !important; float: none; font-family: "Helvetica Neue", Helvetica, Arial, sans-serif; font-size: 14px; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px;"><span style="font-family: times;"><i><u>.</u></i></span><span><span style="font-family: times;"><i><u> </u></i></span><br /></span></span></p>

How Could Surface Minerals Get in Diamonds Found in The Deepest Depths of The Earth?

  Diamonds that formed hundreds of kilometers deep below Earth's surface contain traces of chemical reactions that took place on the bot...

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Scientists Create Crystal Stronger Than Diamond

<p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-IdSF8YDv6kU/YGXqBGf0NaI/AAAAAAAAS7w/FxznrEwQuFIk-qYENQS0FDCPTJ8QfP3AACLcBGAsYHQ/s1245/Scientists%2Bhave%2Bmade%2Ba%2Bdiamond%2Bthat%2527s%2Bharder%2Bthan%2Bdiamond%2B%25281%2529.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="790" data-original-width="1245" height="406" src="https://1.bp.blogspot.com/-IdSF8YDv6kU/YGXqBGf0NaI/AAAAAAAAS7w/FxznrEwQuFIk-qYENQS0FDCPTJ8QfP3AACLcBGAsYHQ/w640-h406/Scientists%2Bhave%2Bmade%2Ba%2Bdiamond%2Bthat%2527s%2Bharder%2Bthan%2Bdiamond%2B%25281%2529.jpg" title="Scientists Create Crystal Stronger Than Diamond" width="640" /></a></div> <br /><p></p><p> Currently, diamond is regarded to be one of the hardest and most scratch-resistant natural materials in the world. Most diamonds found in nature and often used in jewelry display a cubic crystal structure, a repeating pattern of 8 atoms forming a cube with carbon atoms at its vertices. Each carbon atom forms four bonds with its neighbors, explaining the overall stability and hardness of the crystal structure.<br /></p><p>Nature's strongest material now has some stiff competition. For the first time, researchers have hard evidence that human-made hexagonal diamonds are stiffer than the common cubic diamonds found in nature and often used in jewelry.<br /><br />Named for their six-sided crystal structure, hexagonal diamonds have been found at some meteorite impact sites, and others have been made briefly in labs, but these were either too small or had too short of an existence to be measured.<br /><br />Now scientists at Washington State University's Institute for Shock Physics created hexagonal diamonds large enough to measure their stiffness using sound waves. Their findings are detailed in a recent paper in Physical Review B.<br /><br />"Diamond is a very unique material," said Yogendra Gupta, director of the Institute for Shock Physics and corresponding author on the study. "It is not only the strongest -- it has beautiful optical properties and a very high thermal conductivity. Now we have made the hexagonal form of diamond, produced under shock compression experiments, that is significantly stiffer and stronger than regular gem diamonds."<br /><br />Researchers have long wanted to create a material stronger than natural diamonds, which could have a variety of uses in industry. While many theorized that hexagonal diamonds would be stronger, the WSU study provides the first experimental evidence that they are.<br /><br />Lead author Travis Volz, now a post-doctoral researcher at Lawrence Livermore National Laboratory, focused his dissertation work at WSU on the creation of hexagonal diamonds from graphite. For this study, Volz and Gupta used gunpowder and compressed gas to propel small graphite disks about the size of a dime at a speed of around 15,000 miles per hour onto a transparent material. The impact produced shockwaves in the disks that very rapidly transformed them into hexagonal diamonds.<br /><br />Immediately after impact the researchers produced a small sound wave and used lasers to measure its movement through the diamond. Sound moves faster through stiffer material. Previously sound moved fastest through cubic diamond; in the lab-created hexagonal diamonds it moved faster.<br /><br />Each process happened in several billionths of a second, or nanoseconds, but the researchers were able to make the stiffness measurements before the high velocity impact destroyed the diamond.<br /><br />Stiffness is the ability of a material to resist deformation under a force or pressure -- for instance, a rock is stiffer than rubber as rubber will bend when pressed. Hardness is the resistance to scratching or other surface deformations.<br /><br />Generally stiffer materials are also harder, said Volz. While the researchers weren't able to scratch the diamonds to test hardness directly, by measuring the diamonds' stiffness, they can make inferences about their hardness.<br /><br />If the science advances to the point where lab-made hexagonal diamonds can be created and recovered, they could have a range of uses.<br /><br />"Hard materials are useful for machining capabilities," said Volz. "Diamond has been used for a long time in drill bits, for example. Since we found that the hexagonal diamond is likely harder than the cubic diamond, it could be a superior alternative for machining, drilling or any type of application where the cubic diamond is used."<br /><br />While the industrial advantages are clear, Gupta said it is still possible hexagonal diamonds could one day be used on engagement rings. Currently lab-made cubic diamonds have less value compared to their natural peers, but hexagonal diamonds would likely be more novel.<br /><br />"If someday we can produce them and polish them, I think they'd be more in-demand than cubic diamonds," said Gupta. "If somebody said to you, 'look, I'm going to give you the choice of two diamonds: one is lot more rare than the other one.' Which one would you pick?" </p><p><br /></p><p><i><u><span style="font-family: trebuchet;">The above story is based on <a href="https://news.wsu.edu/2021/03/31/lab-made-hexagonal-diamonds-stiffer-natural-diamonds/" rel="nofollow" style="-webkit-text-stroke-width: 0px; background-color: white; border-radius: 0px !important; box-sizing: border-box; color: #004276; font-size: 14px; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;" target="_blank">Materials</a><span style="-webkit-text-stroke-width: 0px; background-color: white; color: #333333; display: inline !important; float: none; font-size: 14px; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><span> </span>provided by<span> </span></span><a href="http://www.wsu.edu/" rel="nofollow" style="-webkit-text-stroke-width: 0px; background-color: white; border-radius: 0px !important; box-sizing: border-box; color: #004276; font-size: 14px; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;" target="_blank"><strong style="border-radius: 0px !important; box-sizing: border-box; font-weight: bold;">Washington State University</strong></a><span style="-webkit-text-stroke-width: 0px; background-color: white; color: #333333; display: inline !important; float: none; font-size: 14px; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">. Original written by Sara Zaske.</span></span></u></i></p>

Scientists Create Crystal Stronger Than Diamond

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