At a glance, diamond and graphite are totally different. Diamond is a precious gem reserved for fancy jewelry. Graphite is found in common pencil lead. Yet diamond and graphite are made of the same stuff: carbon atoms. The difference is how those atoms are arranged.
The sheets of carbon atoms in graphite peel apart easily. That’s why graphite rubs smoothly off the tip of a pencil and onto paper. In diamond, carbon atoms are locked together in a crystal lattice. That rigid pattern, which is the same in all directions, gives diamond its strength and durability.
Forging diamond requires high heat and pressure. Those conditions are found deep inside Earth’s mantle — at least 150 kilometers (93 miles) below ground. Some “super-deep” diamonds may be born as deep as 700 kilometers (435 miles) down. Diamonds ride to Earth’s surface through volcanic eruptions. Those gems retain their crystal structure even under the much lower pressures found above ground. And lab experiments show these minerals hold up under super high pressures, too. Diamonds don’t buckle even under five times the squeeze felt at Earth’s core.
Earth isn’t the only place to form diamonds. Gems found in one space rock may have been forged inside a planet that broke apart in the early solar system. Diamonds are also born under the intense heat and pressure of violent collisions. Mercury may be covered with diamonds due to meteorites flash-baking its carbon crust into crystal. If so, that planet may host a stockpile of diamonds many times the size of Earth’s.
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Rare blue diamonds form deep, deep, deep inside Earth The rare blue diamonds may include boron, seawater and massive rock collisions. Blue diamonds are among the rarest of gems. Earth’s mantle is that deep, hot layer between Earth’s crust and core. And it’s here that these diamonds are born. Yet their blue hue comes from boron, an element not commonly found there. Scientists now think they’ve figured out how the boron got there. Their analyses suggest that sinking pieces of Earth’s crust ferried the boron deep down from the crust. If true, the blue gems’ birthplace is among the deepest of any diamonds.
Evan Smith and his colleagues made the new findings. Smith is a geologist at the Gemological Institute of America, based in New York City. That institute has studied millions of diamonds from around the world. Only a small share of them — about two in every 10,000 — are blue. And only a few blue diamonds have tiny bits of non-diamond material, called mineral inclusions, inside their crystal structure.
Diamonds and more suggest unusual origins for asteroids Diamonds found in one asteroid may have formed deep inside a Mars- or Mercury-sized planet that got smashed in the early days of the solar system.
A space rock that fell to Earth a decade ago may once have been part of a planet. It would have been a planet that met its end in the solar system’s early days, new data indicate. Inside this meteorite, scientists found tiny pockets of iron and sulfur. They were wrapped in diamonds. Those crystal gems formed under high pressure, the researchers say — likely inside a planet the size of Mercury or Mars.
Extreme pressure? Diamonds can take it Diamond retains its structure even at extreme pressures, which could reveal how carbon behaves in the cores of some exoplanets.
Diamond holds up under pressure — lots and lots of pressure. The crystal maintained its structure in laser experiments that reached more than five times the pressure at the center of the Earth.
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