00:00So, here's a quick question. Where's the biggest stash of gold on Earth?
00:06Well, thanks to the movies, my first thoughts go to Fort Knox, the iconic U.S. vault known for its security and secrecy.
00:14But no, that's not it. Potentially, more than 99% of Earth's gold might not be in any vault.
00:22It's likely hidden deep inside the planet, in the core.
00:26And now, scientists say, we might not need to dig 1,800 miles to get to it.
00:32Because some of that gold, it might be making its way up, oozing through a volcano.
00:38But first, what makes gold so interesting and valuable?
00:42Well, gold has always been more than just a shiny metal.
00:45It shaped economies and driven empires.
00:48The first pure gold coins were created in 540 BCE by King Croesus of Lydia,
00:55an Iron Age kingdom located in what is now modern-day Turkey.
00:59As a metal, it's rare, but not too rare.
01:03It's a great conductor of electricity and heat.
01:06It doesn't rust, tarnish, or react much with anything.
01:11It's easy to melt, mold, carry, and measure.
01:14And on top of all that, it's beautiful, durable, and incredibly useful.
01:19Not just for jewelry, but also in electronics, medicine, and space tech.
01:25Yep, it's even used to coat astronaut helmet visors and spacecraft to reflect harmful infrared radiation.
01:33Humans have mined about 200,000 tons of gold,
01:37which is enough to make a cube that's roughly 72 feet on each side.
01:41Since gold doesn't really break down, a lot of the gold we use today could actually be really old,
01:49even dating back to prehistoric times.
01:52It's also one of the most hoarded and secretly stashed valuables on Earth.
01:56Between private collections, national reserves, and heirloom jewelry passed down through generations,
02:02we might never know exactly how much is really out there.
02:06But we do assume that 99.99% of it is still trapped within Earth's core.
02:13So, how can there be gold within the core, and what does that mean?
02:19Right under our feet is Earth's outer skin, the crust.
02:23It might feel solid and massive to us, but compared to the rest of the planet, it's paper thin.
02:28Beneath that is the mantle, which is basically a giant layer of hot rock.
02:35It's not quite solid, not quite liquid, more like a slow-moving putty that flows over time.
02:42Then we have the outer core, which is a swirling sea of molten metal, mostly iron and nickel.
02:48It's spinning around and creating Earth's magnetic field.
02:51And in the very center is the inner core, a solid metal ball, hotter than the surface of the Sun,
02:58but still solid because the pressure down there is extremely high.
03:03When Earth was first forming, it was super hot.
03:07So hot that the entire planet was like a giant cosmic lava lamp, bubbling with molten metal and rock.
03:14In that state, every element could move freely, and the heaviest one sank toward the center.
03:19Gold, along with other dense metals like platinum and ruthenium, is really heavy.
03:24So those metals naturally sank to the core in a process called planetary differentiation.
03:31Think of it like oil and water in a bottle.
03:34If you shake it and then let it settle, the heavier substance sinks to the bottom,
03:38and the lighter one rises to the top.
03:40In Earth's case, lighter materials floated upward and eventually formed the crust.
03:46Now, gold has a really cool characteristic.
03:49It really likes to stick to iron.
03:52That's why scientists call gold a sidrophile, which literally means gold-loving.
03:57So when iron started sinking, gold followed it down, straight to the center of the planet.
04:04On top of that, gold is super heavy, nearly 20 times heavier than water.
04:09So gravity helped pull it even deeper.
04:12That's why today, the Earth's crust only has tiny traces of gold,
04:17while the other 99% remains unreachable in the core, 1,800 miles below our feet.
04:23But that's not all.
04:26Some theories suggest that maybe 200 million years after Earth was formed,
04:31the planet got hit by a bunch of metal-rich meteorites.
04:35Those space rocks were loaded with gold.
04:37And since Earth's crust had already cooled by then,
04:41that gold stayed near the surface.
04:43And we've been using it ever since.
04:44So if most of Earth's gold is trapped below,
04:49what exactly was discovered oozing out?
04:52Well, scientists recently studied volcanic rocks in Hawaii.
04:56And they found out that these rocks contained a rare version of the element ruthenium,
05:01which is called ruthenium-100.
05:04Now, this little isotope isn't something you usually find hanging out near the surface.
05:08It has a kind of chemical footprint that says,
05:12Hey, I came from way down deeper.
05:15And when we say deep, we mean core-mantle-boundary-deep,
05:19the layer where Earth's molten metal core meets the rock above it.
05:23Basically, it's the basement no one thought you could access.
05:27The basement where we assume that gold is hiding.
05:30So how do these rocks get from the core all the way up to Hawaii?
05:35Vacation!
05:36Well, no.
05:37Actually, it all comes down to something called a mantle plume.
05:41We know that the lower part of Earth, near the core, is insanely hot.
05:46Every now and then, a big, superheated blob of rock starts rising through the mantle.
05:51Slowly.
05:52Like, really slowly.
05:54We're talking a few inches per year.
05:56But over millions of years, that adds up.
06:00This rising column of hot rock is the mantle plume.
06:04It doesn't blast upward like a volcano.
06:07It slowly rises and carries material from deep, deep inside the Earth.
06:11That includes elements and chemical fingerprints from the core-mantle-boundary.
06:16However, here's the cool part.
06:18When that plume finally reaches the surface,
06:21it punches through the crust and creates a volcanic hot spot.
06:24That's what happened in Hawaii.
06:27The islands were literally built by this deep-earth plumbing system.
06:32The lava that erupts there isn't just melted surface rock.
06:36It's a blend of material that's been on a journey from thousands of miles below.
06:40But I can hear your thoughts now.
06:43Wait, what about gold?
06:45Well, sadly, we're not talking about gold bars coming from a volcano.
06:50What's actually leaking is tiny atomic-level traces of metals like ruthenium.
06:56However, where there's ruthenium, there's a good chance gold is tagging along.
07:01Remember when we said that gold is a siderophile, meaning that it really likes iron?
07:06Well, the ruthenium has the same property.
07:10It's an iron-loving element, which means it tends to bond with iron
07:13and sink to the core during planet formation.
07:17So if ruthenium from the core is managing to ride up to the surface through mantle plumes,
07:23it strongly suggests that gold and other similar heavy metals could be doing the same.
07:29In other words, scientists are using ruthenium as a chemical trail marker
07:33because it's easier to detect and analyze.
07:36Meaning that gold might be there too,
07:39just in amounts too small to measure with current instruments.
07:43This discovery suggests that all the siderophile elements are leaking out of the core.
07:49But this opens an opportunity to ask,
07:52has this happened before?
07:54And if so, what could it mean?
07:56Well, maybe Earth's core has been leaking metals all along,
08:00and we just never noticed.
08:01The truth is, we're still just scratching the surface, or in this case, the core.
08:08For all we know, this kind of deep Earth leak has been going on for millions,
08:13maybe even billions of years.
08:15But until now, we haven't had the tools to notice.
08:18The technology that scientists use to spot ruthenium-100 is brand new.
08:24It has only recently become precise enough to pick up these tiny chemical hints.
08:29So this might be the very first time we've caught Earth's core doing this.
08:34And if that's true, it's kind of a big deal.
08:38Because it means the inside of our planet isn't sealed off in silent.
08:42And it might still be shaping the surface in ways we never imagined.
08:47Not with explosions and earthquakes,
08:50but with slow, steady, atomic-scale signals rising through the rock,
08:55we're only just beginning to detect these signals.
08:58And if rare metals are making that journey upward,
09:02there's a lot more happening deep inside Earth than we thought.
09:05This isn't just a one-time discovery.
09:08It could be the start of a whole new way of understanding our planet.
09:13Cool, huh?
09:16That's it for today.
09:17So hey, if you pacified your curiosity,
09:19then give the video a like and share it with your friends.
09:22Or if you want more, just click on these videos and stay on the Bright Side!
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