You know, When it comes to finding diamonds in the ocean, you probably think about sunken
treasures that went down with pirate ships and Spanish galleons. Maybe you’d like to
find the Flor de la Mar, which sank in 1511 and took with it 200 chests of treasure, including
diamonds the size of your fist!
If you’re set on looking for underwater fortunes, there’s just two problems:
First: finding sunken treasure is no easy feat. People have been looking for the Flor
de la Mar for over 500 years! Second: “Finders keepers, losers weepers”
doesn’t apply here. You may have to give the diamonds back. I don’t mean drop them
back into the ocean to avoid Davy Jones’s curse – I mean return them to the country
of origin. International law is tricky. The only people sure to get rich are the lawyers.
(That’s why mom wants you to go to law school!)
But there are lots of diamonds at the bottom of the sea that didn’t go down with a ship.
How did they get there?
Well, natural diamonds – not the ones we make (but more on those later) – come from
the Earth’s mantle, 100 miles or more beneath our planet’s surface. If you could hop in
your car and drive that distance, it’d take you 2 hours at highway speeds! That’s a
long way, a much longer trip than, say, going to the deepest anyone has ever drilled into
the Earth’s crust – that’d be less than 8 miles! Not even a tenth of the way to the
diamonds!
So, if they form so deep, how do any end up here with us on the surface?
If you guessed—Boom! —Volcanos! —Nice job! You get brownie points!
When volcanos erupt, it’s a lot like when you burp. Seriously, imagine you’re standing
in a hole with just your head sticking out. Your head is the visible mountainous part
of a volcano. Your buried body is all the stuff bubbling underground. When you burp,
hot gasses from deep in the Earth—or your stomach—rise up. With a volcano, if the
lava spews up from a deep enough layer (like 100 miles down), then diamonds shoot out!
Ok, but what about the diamonds in the ocean? Are there volcanos underwater?
Why, yes – yes, there are!
Volcanos erupt when the tectonic plates beneath them move around. This releases all kinds
of hot stuff underneath (those lava “burps”). When the same thing happens underwater, it’s
called a “subduction zone.” That’s a term you won’t hear much outside of geology.
If it reminds you of the word “submarine,” there’s a good reason for that. You see,
“sub” means “under,” and “marine” means “water.” That’s why some people
call the seafloor type of diamonds the “marine” kind.
A subduction zone is a place where huge tectonic plates shift around underwater. When one plate
slides under another, it’s kind of like sticking a shovel into the mud and lifting
up the dirt. Worms pop out!
They do that because you disturbed them. Disturb a sleeping dog, it wakes up and moves. Disturb
sleeping diamonds, and they move too. Some diamonds will sink deeper into the Earth,
just like some of those worms might. But other diamonds will move up, especially if the tectonic
plate releases hot gas and lava. The reason? Because heat rises and carries the diamonds
up with it!
But how do diamond-hunters find subduction zones all the way at the bottom of the ocean?
Good question because it’s not easy, even for scientists! So, some people save themselves
the trouble and make their own diamonds!
You can make a diamond from anything with carbon in it. Yep, even burnt toast! Just
gotta add heat and pressure. But you can’t do it at home because, well, your toaster
isn’t hot enough. Your pressure cooker won’t work either.
In a lab, they make diamonds using something called H. P. H. T. That stands for High Pressure,
High Temperature. And “high” is an understatement. The pressure they use is 725,000 pounds per
square inch. It’d be like having a mountain drop on your foot. Ouch! As for the temperature,
does 2,000°F sound high enough to warrant that “H” in H.T.? And, yeah, that’s
as hot as lava, which makes sense – diamonds come from volcanos, right?
While nowhere near as pretty as natural diamonds, these human-made, or “industrial” diamonds
have plenty of uses:
If you’ve seen fake diamonds, they might be made of glass. That glass was probably
cut with an industrial diamond. Whether it’s artificial or au-natural, diamond is one of
the hardest substances on Earth – it can cut just about anything. From the drills that
your dentist uses on your teeth to the saws that cut through trees and metal, all sorts
of blades are made with industrial diamonds.
Diamonds are also great conductors of heat, and they can withstand high temperatures.
Think about it: you can’t put anything on the stove. A piece of wood will catch fire.
Plastic will melt. If you’ve cooked eggs in a pan, you can be sure that pan was made
of metal because metal conducts heat. That means it absorbs heat into itself and spreads
it around nice and even so that your eggs cook just right! But diamonds do this even
better! That’s why you can find them inside electrical equipment, and—yep—the coating
on cookware!
Some facial exfoliators even have ground-up diamonds in them! The crushed gems work like
sandpaper to scrape off rough skin and reveal a fresh new complexion!
Ok, let’s reel it in here. The seafloor is teeming with diamonds. Next question: is
it possible to get them? If so, how can I do it?!
Oh yeah, it’s possible alright. People are harvesting diamonds from under the sea right
now as you watch this video! But most of them don’t come from deep tectonic subduction
zones. They come from rivers.
You see, rivers run through all kinds of terrain, and they carry a little of whatever they wash
over with them as they flow along. This hitchhiking passenger is called sediment. It’s the stuff
at the bottom of a river. Sediment is mostly made up of shells, grit, and silt: the usual
things you’ll find underwater. The river’s current carries sediment downstream.
And if the river washes through a diamond mine? The sediment will have diamonds! The
river washes those diamonds downstream until, at last, it dumps them into the sea. These
diamonds are easier to find than pirate treasure or a subduction zone. Just look for sparkles
where the river mouth empties into the ocean!
How did they figure this out?
The first clue probably came from the Orange River in South Africa. This body of water
meanders through all kinds of rock and has been famous for diamonds since the 1800s.
That’s when people started finding dazzlers like the Eureka Diamond— originally weighing
over 21 carats —on its banks.
The Eureka wasn’t the only one. People kept finding more, and they still do today! Treasure
hunters have been digging up the banks of the Orange River for 200 years, which is why
diamonds are getting harder to find. You might imagine scuba divers with flashlights toilfully
hunting for prismatic gleams. (Ohh, somebody’s been using their thesaurus!)
That might work for a diver who only wanted one diamond and maybe a shell, but companies
like De Beers, a big shot in the diamond industry, have found a more efficient method.
Think of it this way: if you spilled some sand on your shag carpet and you wanted to
get it up, you wouldn’t use a broom. The bristles would only drive the grains deeper
into the carpet’s fibers. If you tried to sweep up diamonds, you’d just push them
under the ocean floor.
You could crawl around your carpet with a flashlight and a pair of tweezers, like our
scuba diver, carefully extracting each grain one at a time. That would work, and you would
… eventually … collect a few grains. But you’d miss your soccer game…and dinner…and
probably bedtime. And maybe next year! It would take forever, and you’d miss a lot
of that “precious” sand!
But you wouldn’t do that! You’d simply vacuum the carpet and have that stuff up in
no time! And that’s what the people at De Beers are doing. They figure out where the
river spills its sand—make that, diamonds—on the ocean floor. Then, they send out ships
that look something like oil tankers. But instead of carrying oil, these vessels have
giant vacuums that reach through the water and suck up those sparklers!
Of course, they suck up a lot of other stuff too, but they don’t mind sifting through
it. I mean, if you’d swept up diamonds (instead of sand), you’d happily open up your vacuum
cleaner bag and sort through the dirt and dog hair to find them. It might be yucky,
but it’d be worth it!
In fact, maybe you should go vacuum the living room right now, you know, for practice. After
all, there are a lot more diamonds at the bottom of the ocean just waiting to be claimed!
Ah, I can hear the new Beatles song now: Lucy in the Muck with Diamonds… nah.
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