10 Lustrous Facts About Gold
Gold’s symbol on the periodic table, Au, comes from its Latin name aurum, which means “glowing dawn.” This metal’s tantalizing yellow color and shining exterior has made gold a prized element in jewelry and treasured objects for thousands of years—but, amazingly, all of the gold that has ever been refined could melt down into a single cube measuring 70 feet per side. Read on for more opulent facts.
1. GOLD WAS PROBABLY THE FIRST METAL USED BY HUMANS.
Gold, number 79 on the periodic table, is almost twice as heavy as iron, but it’s incredibly malleable—and for that reason, it was probably the first metal humans ever wrought. The oldest known worked-gold artifacts, from the Thracian civilization in present-day Bulgaria, date back 4000 years; the death mask of the ancient Egyptian pharaoh Tutankhamun contains about 220 pounds of gold. Despite its presence in world cultures for millennia, “more than 90 percent of all of the gold ever used has been mined since 1848,” according to the American Museum of Natural History. That year marked the discovery of gold at Sutter’s Mill, California, launching the California Gold Rush.
2. ALL OF THE GOLD IN THE UNIVERSE MAY HAVE COME FROM COLLIDING NEUTRON STARS.
In 2017, astronomers from the University of California, Berkeley and other institutions observed two massive neutron stars spinning around one another at an accelerating rate. When the two stars—each with a mass up to twice that of our Sun—finally collided, gravitational waves rippled through the universe and clouds of neutron-rich material shot out. For the first time, researchers observed red light emanating from the collision, indicating the production of heavy metals like uranium, gold, and platinum. The finding supports the theory that all of the gold in the universe was formed this way—and that particles of that gold arrived on Earth in meteorites billions of years ago.
3. IT’S AN EXCELLENT CONDUCTOR OF ELECTRICITY.
Gold efficiently transfers heat and electricity—though not as well as copper and silver. In general, some metals conduct electricity well because their atoms share electrons easily: As electrical current flows, electrons move along in the same direction with just a little voltage. (The opposite would be true of insulators like glass, in which electrons move only when compelled to do so by thousands of volts of electricity.) Because gold resists oxidation and corrosion, it continues to move electrons even if occasionally exposed to the atmosphere. That’s why electrical contact surfaces are plated with a microscopic gold coating in smart phones, airbag sensor modules, and other devices.
4. YOU CAN FIND SUNKEN TREASURE, BUT YOU MIGHT NOT GET TO KEEP IT.
In 1985, Florida diver Mel Fisher located the Nuestra Señora de Atocha, a famed Spanish naval ship loaded with valuables that had sunk in a hurricane in 1622. Fisher’s motto was “finders, keepers”—and in the following decades, he retrieved gold, silver, emeralds, and pearls worth millions of dollars. Under admiralty law, Fisher was entitled to keep what he found, but archaeologists, historians, and conservationists protested. Two years after the discovery, Congress passed a law stating that riches found in wrecks within three miles of a U.S. coastline belong to the adjacent states.
5. GOLD CAN BE MEASURED WITH A UNIT FROM THE MIDDLE AGES …
The gold standard is a monetary system that ties a currency’s value to gold itself, which theoretically keeps inflation in check. The United States adopted this standard in 1879, but began to abandon the system in 1933 to stimulate the economy at the height of the Great Depression. The U.S. got rid of the gold standard entirely in 1971.
However, the U.S. Treasury still holds on to 261.5 million fine troy ounces of gold, using a unit of measurement that dates to the Middle Ages and is named after the city of Troyes, France. (A troy ounce is a few grams heavier than a regular ounce.) The goods are in the form of gold bullion (bulk gold shaped into bars), as well as coins and miscellaneous units, and stored in vaults at federal mints and reserve banks. As of September 2017, the government’s gold reserves total $335.5 billion in market value.
6. … OR IN BREAD.
Gold’s value has remained surprisingly steady over time. “King Nebuchadnezzar of Babylon, reigning in the 6th century BCE, bought 350 loaves of bread for an ounce of gold,” John Mulligan, head of member and market relations at the World Gold Council, tells Mental Floss. Roughly 2500 years later, with the current price of gold at about $1200 per ounce and a loaf of bread at $2.50, an ounce of gold would buy 480 loaves. “If we also then look at how gold compares with the historic purchasing power of the world’s major currencies over the last century or more,” Mulligan adds, “we see none of them has endured like gold.”
7. GOLD MIGHT HELP DESTROY CANCER.
“Gold just sits there and shines when it’s [in a] large [mass]—it doesn’t do much,” Mostafa A. El-Sayed, a leading chemist at the Georgia Institute of Technology, tells Mental Floss. “But when you cut it smaller and smaller, all of the sudden, it has different properties.” In a 2017 paper in Proceedings of the National Academy of Sciences, El-Sayed placed gold nanorods in mice with tumors and zapped the nanorods with a laser. The rods became hot enough to kill the adjacent cancer cells. Fifteen months later, the mice showed no long-term toxicity. In the paper on these findings, El-Sayed and his co-authors called this “a strong framework” for trying the technique in humans.
8. GOLD HAS BEEN USED IN DENTISTRY FOR AT LEAST 4000 YEARS.
Gold’s combined properties of malleability and biocompatibility (i.e., it can be tolerated inside the body) have made it useful in dentistry. Archaeologists have found gold dental modifications in skulls from Southeast Asia dating back 4000 years. The Bolinao skull, an artifact from the 14th or 15th century, is one of 67 skulls featuring decorated teeth that have been excavated in the Philippines. Ten-millimeter-wide gold plates are fixed in place on the incisors and canines in an overlapping fish-scale pattern. Today, gold-alloy crowns are still used to cap worn-down teeth or to strengthen weakened teeth.
9. NASA USES GOLD IN SPACE TECHNOLOGY.
The visors of astronauts’ space suits are coated with a layer of gold that’s just 0.000002 inches thick. The coating shields their eyes from the Sun’s harmful infrared light while allowing visible light in. That same ability to reflect infrared light will be put to work in the James Webb Space Telescope as it searches for light from the first stars and for potentially habitable exoplanets. The telescope will be equipped with 18 hexagonal mirrors in a honeycomb-like structure. Three grams of gold were vaporized in a vacuum chamber and then adhered to the telescope’s mirrors, which are made of beryllium. The layer of gold is just 100 nanometers thick—a tiny fraction of the thickness of a sheet of paper.
10. COLORADO’S CAPITOL BUILDING IS GILDED WITH PURE GOLD LEAF.
At least 10 state capitol buildings have gold-topped domes: Colorado, Connecticut, Georgia, Iowa, Massachusetts, New Hampshire, New Jersey, Vermont, West Virginia, and Wyoming. Colorado’s dome was restored in 2013 using about 65 ounces of pure gold that was mined in the state and hammered into leaves between one-8000th and one-10,000th of an inch thick. Gilders applied 140,000 3-inch squares of gold leaf to sticky copper plates that were then laid on the building’s dome. “The work is as much an art as a science due to how thin and fragile the gold leaf really is,” Doug Platt, communications manager for the state’s Department of Personnel and Administration, tells Mental Floss.