13 Facts You Probably Never Knew About Gold

Check out these fun 24-karat nuggets about gold.

Pure gold is stretchy

Pure gold is so ductile (translation: stretchy), a single ounce of it can be drawn out into a thread 50 miles long without breaking (at which point it also would be too thin to see). If you did this to all of the existing gold in the world, it would wrap around the earth 11 million times.

You shouldn’t bite gold

Contrary to popular belief, biting on gold is not a reliable way to tell whether it’s genuine—other metals are also soft enough to show teeth marks. And though many champs chomp down on their prizes, Olympic gold medals haven’t been made from that metal since the 1912 Summer Games in Stockholm. Modern gold medals are mostly silver; those from the 2016 Games in Rio contained only 1.2 percent gold.

The Nobel Prize is made of gold

The Nobel Prize medal is still made of gold, though it was downgraded in 1980 when it went from 23 karats (24 is pure) to an 18-karat core coated in 23-karat gold. The gold in each medal is worth about $8,000.

Gold can change color

A naturally yellow element, gold changes color when it is mixed with other metals, which also gives it added strength. White gold contains nickel or palladium. Rose gold gets its hue from copper. There’s even green gold, which has silver and sometimes zinc or cadmium. To determine how much gold is in any piece, divide the karat content by 24 and multiply by 100. The ­resulting percentage is the amount that is gold.

Gold has been used in medicine for millennia

The ancient Romans made dental bridges out of it, a practice they learned from the Etruscans. For much of the 20th century, doctors reduced their rheumatoid arthritis patients’ pain and swelling with intramuscular injections of gold compounds that have anti-­inflammatory properties. Today, some oncologists use gold compounds to shrink cancerous tumors.

Gold has to get really hot to remove impurities

The term bullion, which refers to gold bars or coins ready to be traded, comes from the Latin word for boil. That’s how to remove gold’s impurities—at a mere 5,173 degrees F.

The U.S. Treasury currently holds 147.3 million ounces of gold bullion

About half of it is stored at Fort Knox, a stash that’s worth more than $130 billion. Security at Fort Knox is so tight, only one president has ever been inside the vaults: Franklin Delano Roosevelt, the same president who effectively took us off the gold standard in 1933. (The United States didn’t fully abandon it until 1971.)

Most of the world’s gold is now mined in China

The country overtook South Africa for total historical gold production in 2017. But the world’s largest gold crystal—an extremely rare geometric formation that can appear on gold specimens—weighed 7.7 ounces and was found decades ago in Venezuela.

Some gold comes from sewage

Among the more surprising—and unpleasant—sources of gold: treated sewage. In 2015, after analyzing sewer sludge from local treatment plants, researchers at Arizona State University concluded that the sewage produced each year in a city of a million people includes, on average, $2.6 million worth of gold and silver.

We’ve extracted about 80 percent of the world’s gold

We have already extracted about 80 percent of the world’s 244,000 mineable tons of gold. Ocean waters and seabeds contain about 20 million more tons, but this treasure remains largely untouched because of the prohibitive costs to tap it. But the biggest trove is in outer space. One asteroid alone (called 16 Psyche) has a few hundred quintillion ­dollars’ worth.

But so far, we’ve only brought gold to space, not taken any from it

Space suits and spacecraft are coated in gold to reflect harmful infrared ra­diation from the sun. Any instrument NASA wants to keep cool gets a gold coating as well (since radiation is also a great source of heat). This includes the James Webb telescope, the world’s most power­ful space telescope, set to be launched later this year.

Pyrite is the mineral known as fool’s gold

Pyrite, the mineral better known as fool’s gold, has fooled many, including Christopher Newport, one of the founders of the Jamestown colony, who sailed a shipload of it to London in the 1600s. Although pyrite can be a disappointing find, it is often dis­covered near sources of real gold, so a miner who stops digging once he finds a piece of pyrite may be the real fool.

Don’t go looking for a pot of the precious metal at the end of a rainbow

One version of this legend is more of a cautionary tale: When a poor Irish husband and wife pull the last carrot out of their garden, they catch a leprechaun dangling from it. The leprechaun agrees to grant all their wishes if they find his pot of gold at the end of the rainbow, leaving them to forever chase a fictitious fortune. Here are some other interesting facts that will blow your mind.

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Originally Published in Reader's Digest