Why Are There Diamonds in the Ocean?

The diamond industry pulls stones from the ocean floor in addition to their mining operations. Learn how diamonds form and travel in this episode of BrainStuff, based on this article: https://science.howstuffworks.com/environmental/earth/geology/ocean-diamonds.htm

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff, a production of iHeart Radio. Hey
brain Stuff, Lauren Bogabam Here. If you've ever heard the
slogan a diamond is Forever, then a nineteen forties marketing
campaign is still doing its job. The line was coined
by an ad woman working with the agency that was
with de Beers Group. They're the company credited with almost

(00:23):
single handedly popularizing diamonds and engagement rings from the late
nineteen forties onwards. Yep, that trend isn't even a century old.
De Beers spent decades building a global empire, and some
would call it a cartel around diamond mines that they
owned in countries like South Africa. So why did they

(00:43):
purchase more than three thousand square miles and that's about
seven thousand, eight hundred square kilometers of Atlantic seafloor near
the coast of Namibia. It's simple. Not all diamonds are
found on dry land. Many turn up and sediments below
the ocean's surface. You just have to know where to look.
Carbon is a wonderfully versatile element found in Earth's crust, atmosphere,

(01:07):
and all living things that we know of anyway. It's
also well represented in jewelry stores. Diamonds are made of
carbon atoms that have been subjected to extremely high temperatures
and pressures. The crystals usually have eight sides before being cut,
but six and twelve sided specimens are out there too.
Inside a diamond, every individual carbon atom shares a strong

(01:29):
bond with four others, which makes diamonds ridiculously hard. Rub
one of these gems against almost any other known material
and it'll leave a scratch mark behind. Asteroids can create
the intense heat and pressure needed to produce diamonds when
they strike the face of our planet. Such impact diamonds
are pretty rare, though, and they tend to be small.

(01:51):
You're way more likely to find a diamond from deep
within the Earth, forged somewhere in the ballpark of five
hundred miles under the surface. That's around a hundred forty
d kilometers, and the ocean may have played an underappreciated
role in the history of our world's diamonds supply as well.
Many diamonds contain small quantities of salt. For years, geologists

(02:13):
wondered if this originally came from sea water. A study
published in the journal Science Advances in twenty nineteen bolstered
this hypothesis. It turns out that when a blend of
marine sediments and the volcanic rock peridotite experience high heat
and tremendous pressure in a laboratory setting, you get something
that looks an awful lot like the salts trapped inside

(02:35):
some diamonds. What's this mean for the real world, though,
According to the papers authors, their experiment suggests that most
diamonds come into being after chunks of seafloor are dragged
into Earth's mantle via plate tectonics, and some of the
minerals taken from the ocean during this process crystallize into gems.
Volcanic eruptions later bring the diamonds up to the planet's

(02:57):
surface or pretty close to it. And now, the study
mentioned above doesn't explain whide Biers and other groups are
hunting for diamonds off the African coast, those stones who
are more likely carried out to sea by river currents.
Namibia's southern border is defined by the Mighty Orange River.
For millions of years, it's been grabbing a hold of

(03:17):
diamonds from mainland deposits and relocating them elsewhere on the continent.
Only sometimes this river ferries the stones all the way
out to the ocean. Since the nineteen sixties, treasure seekers
have been dredging up diamonds by the coast lines of
northwestern South Africa and southern Namibia. In twenty eighteen, nearly
seventy five percent of the latter countries total diamond output

(03:40):
came from ocean based mining operations. Most of these gems
are harvested at depths of four hundred two four hundred
and fifty feet that's about a hundred and twenty two
hundred and forty meters below sea level. To accomplish this,
sediments from the ocean floor are sucked up into a
remote controlled crawler vehicle that scuttles across the sea bed.
Fitted with mechanical arm it sends diamond ladden payloads to

(04:03):
the main vessel up above, where machines separate out the crystals.
Drones and two person submarines have both been used to
help these ships find diamond rich areas beneath the waves. Unfortunately, though,
dredging campaigns can have long term consequences for aquatic wildlife.
As a cologist Kirsten Thompson told CNN, in the waters

(04:25):
off the coast of Namibia are an important area for
a high diversity of resident and migratory species such as sharks, whales, dolphins,
and seals. Marine mining removes part of the seabed with
heavy machinery and habitat. Recovery from this type of disturbance
can take decades. Gathering these ocean diamonds by hand with
higher divers in small boats is another option that's been

(04:48):
executed in recent years. Today's episode is based on the
article are there Diamonds in the Ocean on how stuff
works dot com written by mar Mancini. Brain Stuff is
production of I heart Radio in partnership with how stuffworks
dot Com, and it's produced by Tyler Klang. For more
podcasts my heart Radio, visit the i heart Radio app,

(05:09):
Apple Podcasts, or wherever you listen to your favorite shows.