Original subtitles

- [Narrator] Its name equals strength.

[metal clanging]

And it makes up nearly 35% of the Earth.

[atmosphere booming]

- [Louis] When that dying star exploded,

it blasted all over the galaxy.

- [Narrator] It's an essential building block

for everything from skyscrapers,

to weapons of war.

It is one of the most important metals on Earth.

- [Jonathan] The demand is so great

that we run this operation 24 hours a day,

7 days a week, 365 days a year.

- [Narrator] It's in our bridges

and in our blood.

You'll never look at iron the same way again.

[glass shatters]

On "Modern Marvels." More iron.

[upbeat music]

[cogs cranking]

[water bubbling]

[rock music] [metal clanging]

Iron, the most abundant element on Earth,

is the stuff that civilization is made from.

It's everywhere.

From the indispensable heart of our buildings,

cars, ships, tools, and weapons.

[guns banging]

But it's also the foundation of the core of our Earth,

and courses in our very blood.

- Iron's incredibly important to our survival.

It's part of our entire being.

Without iron,

life as we know it wouldn't be possible.

- [Narrator] Iron is invaluable

not just because of its unique strength,

but because extreme heat can make it surprisingly pliable.

- Iron is one of the few things on Earth

that can go from an ore, like this,

through fire and forging,

and become a tool like this

that will last for generations.

- [Narrator] Iron's muscle

comes from its atom's superior ability

to share some of its 26 electrons with other iron atoms,

forming a vice-like bond.

There's no limit to the size

of the resulting lattice structure.

- So that's the secret of its strength,

because the sharing of electrons between two iron atoms

is essentially the glue

that holds a piece of iron metal together.

- [Narrator] As strong as iron is,

it's easily reshaped,

since temperatures over 2,800 degrees Fahrenheit

enable us to break the bonds between its electrons

and melt it.

- You can actually rip apart that glue.

The iron atoms are all floating around

in a liquid soup of iron atoms.

This is very useful for us for a number of reasons.

If you want to, you can pour it into a mold

and essentially cast that iron

into whatever shape that you want.

[upbeat music]

- [Narrator] Iron in the form of steel

is the most recycled material in the world.

[machinery booming]

More than 50 million tons find new light every year

in the United States alone.

- Iron and steel are endlessly recyclable,

such that the steel used in a Model T

could have been used in an ice box,

could have been used in a building structure,

then used in the vehicle you're driving today.

The same iron.

[rock music]

- [Narrator] The Earth's crust is comprised

of about 5% iron ore.

And miners extract about 3 billion tons of it every year.

This enormous open-pit mine in Minnesota

lies over one of the largest deposits of iron ore

in the United States.

[tractor horn beeps]

In 2020, the Cleveland-Cliffs Company

acquired the ArcelorMittal Minorca Mine,

which processes nearly 10 million tons of iron ore a year.

- This pit that we're standing in right now

is about a mile wide by about 3,000 feet in length.

We mine several layers of ore here.

We're right now about 400 feet down

to the bottom of the pit.

Open-pit mining is a methodology of mining

where you excavate and take off the stripping materials,

the waste materials are on top of the ore,

expose the ore,

and essentially in the process

make a giant hole in the ground.

The demand for iron is so great

that we run this operation 24 hours a day,

7 days a week, 365 days a year.

[rocks rumbling]

- [Narrator] Where did all this iron come from?

[atmosphere booms]

[gentle music]

Billions of years ago, long after the Big Bang,

stars created heavy elements within them,

until the stars became supernovas.

One in particular helped create the Earth.

- When that dying star exploded,

it blasted iron and the other elements

all over its area of the galaxy.

When the Earth first formed,

it was a grand mix of elements.

The remnants of the supernova.

And then as that stuff segregated out

into various pockets, the iron, which is very dense,

sunk by and large to the core.

- [Narrator] In fact, 98% of the Earth's core is iron.

But enormous quantities of iron stayed on the Earth's crust.

Sometimes in the form of deposits.

Like a mountain range full of pure iron

that stood in what is now Minnesota.

The first rains that fell on Earth were highly acidic

and dissolved the iron mountains,

creating an iron-rich ocean.

A few hundred million years later,

the dissolved iron solidified and settled to the bottom,

leaving the deposits we mine today.

- Here in Minnesota, we believe we have enough iron ore

to last the mining activity for another hundred years

with the iron that's currently making ore today.

- [Narrator] The ore extracted here

is an iron oxide called magnetite, which is 22% iron.

Until the late 1940s,

American iron miners dug a richer ore,

called hematite at 65% iron.

[cannon booms]

But the enormous demand for iron

during World War I and World War II

severely depleted the nation's hematite resources.

[heroic music]

- This is hematite,

the rock that was initially mined in Minnesota.

It's red in color because of the oxidized iron.

It looks much like the rust you'd find on steel or iron

if it's left to weather.

This is magnetite.

This is what we're mining today.

It's black in color

and has a lower iron content than hematite.

[suspenseful music]

[van humming]

- 10 seconds 'til main blast.

- [Narrator] Getting to the magnetite ore

starts with a bang.

[ground booming]

[frantic music]

Then loaders transfer the blasted ore to production trucks

that haul it away to be processed.

- This is one of our production trucks.

It's 24-feet wide by 21-feet high by 42-feet long.

It can haul 240 tons of iron ore at a time.

[upbeat music]

The whole process from the mining

all the way through to concentration plant

is designed to take these large pieces of iron ore,

make them smaller and smaller and smaller

so that we can separate the iron particles

from the rest of the material.

[frantic music]

- [Narrator] After crushers and grinders

reduce the iron ore to a powder,

mixers combine it with water to form a slurry.

The slurry then passes through magnetic separators.

- The magnetic separators are large drums

that are 10-feet in length, 4-feet in diameter,

and contain stationary magnets.

As the drums rotate,

they pick up the magnetic iron particles that are in the ore

and separate them from the non-magnetic particles.

- [Narrator] Machines mix the iron slurry with clay,

which is then molded and baked at 2,400 degrees Fahrenheit

into convenient, easy-to-transport,

marble-sized pellets.

[rock music]

- This is what it's all about.

Iron ore pellets that contain over 60% iron.

This is our final product, ready for shipment.

- [Narrator] But these little balls are just the beginning

of iron's journey.

Welcome back to more iron on "Modern Marvels."

Iron, it's one of the most abundant elements on Earth.

In North America,

The Great Lakes region is home

to one of the largest deposits in the world.

This mine in Minnesota alone

produces nearly 10 million tons of iron ore per year.

[rock music]

98% of this iron will be used to make steel structures.

From the Golden Gate Bridge,

to stadiums,

to skyscrapers,

they're all made of iron at their core.

To make steel, iron must be 100% pure.

Impurities, which include oxygen, must be stripped away.

Melting the iron is the key to this trick,

in the intense heat produced inside a blast furnace.

The furnace burns coke, a purified form of coal.

- It's called a blast furnace

because the amount of air that is shoved into the system.

It takes incredible amounts of air

to get the temperatures necessary to make steel.

- [Narrator] In the blast furnace,

carbon from the coke is infused into the iron to make steel.

Too much carbon will make it brittle.

So just a small amount, no more than 2%, is all it takes.

- This is a snapshot of what iron looks like

on an atomic level.

When you make steel,

you've actually taken the crystal structure of the iron

and you've crammed a carbon atom into one of the holes

in the crystal structure.

What this does is it makes it harder

for you to slide the iron atoms around

with respect to each other

because you've got this guy crammed in there.

The presence of this carbon atom,

a bad fit as it is between these iron atoms,

is what gives steel its great strength.

- [Narrator] Adding other elements or alloys

to this fusion of iron and carbon

produces a variety of steels that have different properties.

For decades, the iron atoms' flexibility

has helped the steel that surrounds us

to vary greatly in its strength and pliability.

And now with modern computer technology,

experts are able to mix more precise amounts

of alloys to iron,

to produce a new enhanced generation of steels.

- We call them the new advanced high-strength steels.

They are five to six times stronger

than the steels we've used in the past,

making vehicles lighter, safer, and more fuel efficient.

- [Narrator] One industry

incorporating these new advanced high-strength steels

is auto manufacturing.

- The value of these steels in a crash

is their ability to absorb energy.

So rather than the passenger absorbing the energy,

your vehicle structure takes the energy

and keeps the passengers safe.

[metal crashing]

- [Narrator] The new steels have proven

their strength and durability in drop tests,

in which a 400-pound weight drops from 20 feet

to simulate a 35 mile an hour crash.

- This is the result of the drop test.

Here is our sample.

With the old steel, it crushes six inches.

With the new steel, crushes three inches

because of its increased strength

and energy absorption capability.

- [Narrator] If you think adding strength to this new steel

also means adding weight,

think again.

- Here's an automotive component

made with the old technology.

It weighs 40 pounds.

Conferencing the same structure with the new technology,

it's considerably lighter, you can see,

and it weighs 32% less in weight.

- [Narrator] Since the new steels are lighter and stronger,

less is needed to meet crash safety standards.

Today, the typical car body

contains as much as 60% of the new generation of steel

in its construction.

- They'll be applied to the rail and to the bumper

for front impact,

and to the safety cage structure for side impact

and for roof strength,

as well as to the door beams for side impact.

And for rear impact,

they're applied to the rear bumper and to the rails.

- [Narrator] Iron in the form of steel

may save lives on the highway,

but throughout history,

humans have used it as a crucial component

on the battlefield.

[blast booming]

[army radio chattering]

[valiant music]

In fact, iron and the development of weaponry

have gone hand in hand since antiquity.

- Empires that were able to produce the best iron weapons

were the deadliest armies

and those who were able to conquer their foes.

- [Narrator] Iron began revolutionizing warfare

over 3,000 years ago.

- First crude weapons that men used were made out of stones.

These were replaced by bronze.

But when iron came in,

now you had a weapon that could be sharpened,

would keep its edge,

and even last for generations.

[gentle music]

- [Narrator] The first iron weapons

were made with iron extracted from meteorites.

- It was called swords in the heavens.

'Cause you could take meteorite iron,

which was almost pure iron,

and beat out weapons such as knives or swords.

- [Narrator] Whether separating iron from meteorites

in that era,

or smelting it from iron ore,

making iron pliable required extreme heat.

[folk music]

How did the ancients manage it?

Workers built a mound with a hole,

one to two feet in diameter at the center.

They lined the hole with fire-resistant clay or stone.

Next, they placed a layer of charcoal on top of the clay,

which they ignited.

On top of that, they set the iron ore.

Earlier bronze and copper had been smelted the same way,

but smelting iron required an infusion of air

to make the charcoal burn

at iron's higher melting temperature.

- With the air coming in,

that kept the heat at a high enough level.

By heating this up,

the oxygen gets stripped away from the oxide

and carried away with the waste gases from the fire.

And that leaves you with the pure iron.

[metal clanging]

- [Narrator] After workers smelted the iron,

they formed it into a bar called wrought iron.

Ancient weapon makers

then literally beat the wrought iron into shape

in a process called forging.

[fire crackling]

- Okay, the first part of the process in making the knife

is we're gonna make the handle.

I'm hitting it half on and half off of the anvil,

and that stretches this part of the material out

and makes it longer and thinner,

and that'll form our handle.

At forging temperature, or about 1,900 degrees,

the iron is very pliable

so I can take the hammer

and drive it into whatever shape I need.

- [Narrator] Ancient blacksmiths

forged spears, knives, and swords

which were stronger and more durable

than their bronze and copper predecessors.

- This piece of iron now,

after we've done all this work on it,

will last for many generations.

- [Narrator] Iron strength and durability made it ideal

not only for weaponry, but also for defensive purposes.

[valiant music]

For centuries,

wrought iron was the go-to metal for making helmets,

shields, and suits of armor.

- This is very high-quality iron.

It is made for people

who could afford a full suit of armor like this.

And we often take years

to produce one suit of iron armor like this.

- [Narrator] But then, 600 years ago,

that armor would meet a new foe on the battlefield.

Welcome back to "Modern Marvels."

For hundreds of years,

civilizations fought their battles with swords and shields

forged with wrought iron.

[swords clanging] [men shouting]

But then iron weapons took a quantum leap forward,

starting in 16th century Western Europe.

[gun bangs]

- The first muskets that were made, we believe,

were made like small hand cannons

where a sheet of wrought iron was rolled,

and the edges welded together,

and it was formed on the end of a pole or a pike.

[intense music]

- [Narrator] The wrought iron musket barrel

achieved devastating effects on the battlefield.

[gun bangs]

[somber music]

- In the era of forged iron barrel muskets,

plate armor didn't have a chance.

- [Narrator] Beyond the wrought iron used to make muskets

was cast iron.

This was essentially iron melted down to a liquid

which was poured into a mold or cast and then cooled.

- This is an example of cast iron.

This is all one piece.

The advantage of making pieces of cast iron this way

is you can make multiple pieces that are just alike,

and in a very short period of time.

- [Narrator] But cast iron has one major problem.

[iron cracks]

It's brittle.

In 1856, British engineer Henry Bessemer

found a way to make a stronger form of iron

by combining it with carbon in a blast furnace

to make steel.

- Now with steel,

you cut it, you could mill it,

you could shape it in not only a tube,

but also a breech-loading barrel.

With the addition of metallic cartridges,

you could make a very successful

not only breech-loading weapon,

but repeating weapon as well.

[gun clicking]

[ocean swishing]

- [Narrator] In 1862,

the Union and the Confederacy began armoring their warships

during the American Civil War.

- The ironclad ships,

they were made from sheets of wrought iron.

These sheets were applied either to a wooden hull ship,

such as the Merrimack,

or the entire ship was made of sheets of wrought iron

that were riveted together to form the hull

and a turret on top of the deck,

as in the case of the Monitor.

- [Narrator] In their one and only battle,

both ships received dozens of direct hits,

but remained afloat.

In the end, the battle was a draw.

[marching music]

Iron proved to be the real winner,

changing naval warfare forever.

By the 20th century,

iron-rich hematite supplied America's vast steel industry.

In 1915, steel supported a new mechanized war.

- The tanks of World War I were known as landships.

Just like the ironclads of the Civil War

revolutionized naval warfare,

these landships of all steel revolutionized land warfare.

- [Narrator] The iron battlefield helmet,

which first appeared centuries ago,

was reintroduced during World War I.

This time in the form of steel.

- This is an original World War I helmet

as worn by the British and United States troops.

It's made out of thin sheet steel.

It's been stamped the same way you would see a car body.

The idea here is not to protect from bullets.

It is to protect from iron shell fragments

that have been tossed down from exploding shells above.

You see, most soldiers

spent four years fighting in trenches dug in the ground.

- [Narrator] World War II consumed

nearly the last of the hematite iron.

[blast booming]

[guns rattling]

[atmosphere booming]

More than 65 million tons of ore was produced in 1944 alone,

allowing American steel to rule the battlefield,

the oceans, and even the skies.

- We began to use all metal airplanes,

instead of those made of wood

with a canvas fabric coating.

Steel began to replace all other organic materials

for weapons.

- [Narrator] Today, iron is still the most important metal

in every nation's military

as the principle component in all forms of steel.

But one configuration of iron as steel

has proven to be warfare's most dangerous weapon.

The barrel of a gun.

[gun bangs]

[suspenseful music]

The M16 rifle became the US Army's standard issue weapon

in the Vietnam era.

It's plastic, aluminum, and steel construction.

It's designed to be lightweight

and portable in combat conditions.

But to achieve pinpoint accuracy,

gunsmiths at Fort Benning, Georgia, use a heavier steel.

- Getting rid of the plastic, aluminum, when you can,

you end up with a much better product.

And adding iron to the rifle

makes it a much better rifle, a much more accurate,

and much more precise.

[rock music]

- [Narrator] They beef up the M16 rifle

for the elite Army Marksmanship Unit.

- Take a standard issue M16,

and we basically rebuild it

starting at one end to the other.

- [Narrator] The M16 barrel is reinforced

with high-grade chromoly steel.

It's made of over 85% iron

and a critical 1% chromium,

and 0.2% molybdenum.

- Iron is the perfect metal for making rifle barrels.

Due to the fact it will withstand high temperature

and pressures exerted from the bullet,

it will last for a much longer time than some other metals.

[guns banging]

- [Narrator] With each shot,

the barrel must stand up to the force of a bullet

speeding 3,000 feet per second

with a pressure of 65,000 pounds per square inch.

The Army fashions the modified M16 barrel

from a piece of raw stock

called a blank.

- What we're starting with is a nine-pound rifle blank

to make an M16 barrel.

We have to machine the exterior profile.

It's gonna end up being around four pounds,

so we'll take about half that weight off.

You've got areas that

need to be within 1/10,000 of an inch,

which equates to 1/40

of the thickness of a sheet of notebook paper.

And those tolerances have to be extremely tight

for accuracy and reliability.

[upbeat music]

- [Narrator] After rigorous refinements and inspections,

the modified M16 rifle is ready

to challenge the standard issue on the firing line.

- This is a standard M16 rifle.

[guns banging]

This is our modified Marksman M16 rifle,

as you can tell by its custom-made barrel.

[gun banging]

This target was shot with a standard M16 rifle,

and it's about a seven-inch diameter group.

This target was shot with a modified match M16,

and it's about a 1 1/2 inch group.

[gun bangs]

[ships booming]

- [Narrator] Although it has been synonymous with war,

iron is invaluable to modern society.

[upbeat music]

One of iron's most curious properties

provides the motion that powers the machines of our world.

It's magnetic.

[electronic music]

- Magnets are so important to the way the world works.

The forces between magnets, the attractions and repulsions,

can make things move.

[metal clanging]

- [Narrator] This is a super magnet

made of iron combined with a number of other elements,

boron and neodymium.

It is a hundred times stronger

than the magnet on your refrigerator.

- Super magnets can be very dangerous.

They exert such enormous forces on one another,

that if your hand is in the way when they leap,

you're in trouble.

I've put one super magnet inside this wine glass,

and I'm gonna bring the other super magnet up toward it.

[glass shattering]

- [Narrator] This attractive wonder

is the so-called permanent magnet,

an iron bearing metal that retains its magnetism

after the removal of the magnetic force.

That force can either be another permanent magnet

or a jolt of electricity.

Another form of magnet, an electromagnet,

is magnetic only when energized by electric current.

Combine electricity with any piece of iron

and you've got an electromagnet.

- This is a piece of ordinary iron.

It's not magnetic.

It won't pick up the other bolts.

To make it magnetic,

I'm gonna wrap this wire around this bar.

Now, when I run electric current through this coil of wire,

it will turn into a magnet, an electromagnet.

And now it picks up the iron.

But if I cut the power,

the magnetism goes away.

- [Narrator] This property is the key

to movement in electric motors that power our industry.

[electronic music]

An electromagnet called the armature

revolves between the north and south poles

of a stationary permanent magnet

called the stator.

The armature rotates until its north pole

is opposite the south pole of the stator.

The direction of the armature's current

is then reversed.

The two south poles repel each other,

pushing the armature forward.

The current reverses every half turn,

keeping the armature in motion.

[machinery whirring]

Iron is not only an integral part

of the machinery powering our world,

but also a mineral nutrient within each of us,

crucial to our biology.

- The same iron that everybody sees around the world

is the same iron within us

as small microscopic particles.

And without this iron, we will cease to live.

- [Narrator] We help maintain

our body's vital supply of iron

by ingesting iron contained in meat and from vegetables.

Another source is certain brands

of fortified breakfast cereals,

which contain iron baked right into the flakes.

- There actually is a scientific way

of determining the amount of iron present

in a fortified cereal.

- [Narrator] All it takes

is grinding up the flakes into a mash

and using a magnetic stirring bar.

The iron in the cereal is attracted to the magnetic bar.

Then a quick rinse.

- There's about eight milligrams of iron present in a bowl.

When you start the day with a fortified breakfast cereal,

you're actually eating pure iron filings.

- [Narrator] Whatever its source, iron's critical mission

is transporting oxygen through our bodies.

Normally combining iron and oxygen produces iron oxide,

sometimes known as rust.

Which, no surprise, could do our bodies great damage.

But iron which exists in our red blood cells

latches onto oxygen molecules.

So why doesn't it turn to rust?

The body's intriguing solution

is to place the iron in a cage-like molecule called heme.

- Heme is a beautiful cage that is made inside our body.

It captures and encloses the iron in the center

and prevents it from turning to rust

when it binds to oxygen.

[gentle music]

- [Narrator] The iron and oxygen inside the heme

attaches to a protein called globin.

The new molecule, hemoglobin, travels in the blood,

delivering oxygen throughout the body.

[upbeat music]

But the genes that control

this iron-dependent transportation are elusive.

Discovering them is critical,

because estimates are 1.6 billion people,

about 1/4 of the world's population,

are anemic, lacking sufficient supplies of iron and heme.

Anemia can weaken the body's immune system

and trigger life-threatening infections and diseases.

[stern music]

This microscopic transparent worm

may be the key to unlocking the mystery.

70% of its genes are identical to ours

and, like us, it needs iron and heme to survive.

- So what we did

was we took a small amount of iron and heme

and put it on this petri dish

so we can directly look at now

what happens in a transparent animal

as they're actively feeding on this iron and heme.

- [Narrator] Dr. Hamza conducted experiments

that revealed some of the worms digested iron

less successfully than others.

He went on to identify

the missing or mutated genes of those worms,

marking a major breakthrough.

- We were ecstatic

because this will now provide us with a small clue

as to how we transport iron and heme.

This will provide us with the missing link

between iron deficiency and anemia.

[upbeat music]

- [Narrator] With heme, the body may know how to avoid rust,

but rust is everywhere in our environment.

Welcome back to "Modern Marvels."

Iron's hallmark is its strength,

but this indispensable metal girding modern civilization

has one key weakness.

When exposed to wear, or water,

iron turns to rust.

- We don't like rust because it weakens our structures,

our buildings, our bridges,

and it's quite a serious problem.

It's a multi-multimillion dollar industry

trying to control it,

trying to stop it from happening.

[electronic music]

- [Narrator] Rust is the result of a chemical reaction

in which the 26 electrons within the iron atom,

again, come into play.

Two of those electrons orbit the nucleus

farther away than the rest.

- These electrons are sort of like black sheep.

It would make the iron molecule a lot more stable

if these electrons would go away, basically.

Oxygen, on the other hand, needs a couple of electrons,

so it's very eager to take them.

So what happens is they come together, they combine,

and they form a new compound called iron oxide.

- [Narrator] And that's iron's arch enemy.

Rust.

Since the added oxygen makes the iron oxide molecule larger

than the parent iron molecule,

the rust displaces the iron,

and is clearly visible on the surface.

- The main things that we can do

to protect surfaces from rusting are to coat them

and stop the ability of oxygen and water

to get to the surface in the first place.

[upbeat music]

- [Narrator] However, there are some

who don't mind a little rust.

In fact, they want all they can get.

- We love it.

It's rust is us.

- Rockwood Pigments, now owned by Venator Corporation,

is a manufacturer that takes advantage

of iron oxide's beneficial ability

to color our world.

Nature crafts iron oxide,

the same stuff dug up by iron miners,

in a variety of earth tones.

Then manufacturers take iron oxide

derived from leftover iron

and turn it into a variety of pigments.

- We take forms of iron, mostly in scrap steel,

and oxidize it in sulfuric acid,

and then control that reaction

to make different forms of iron oxide.

[upbeat music]

- [Narrator] One ton of scrap metal

makes a ton and 1/2 of pigment,

because of the extra oxygen molecule.

Iron oxide arrives

at the Rockwood Pigments Los Angeles plant every year

in three basic colors.

Red, yellow, and black.

- These are two bulk sacks of iron oxide.

Each one weighs a ton.

Together, it's as much as an SUV.

- [Narrator] Various combinations of

the three pigments enter a blender

where up to five tons can mix at one time.

- Our main concern here

is to make sure that all the red, yellow, and black,

or the combination of pigments,

are mixed together so that we don't get streaks

in the finished product.

- [Narrator] In the quality control lab,

workers mix the powdered pigment

with a liquid binder of clay and water.

This sampled batch is then compared to the standard color

to ensure consistency.

- This is the standard, which we know is good.

This is the batch which we're making.

Obviously we'll be adding some yellow shade red

and sending it back to production for a rework.

This is our standard again, and our batch.

Everything looks good after adjustment.

Ready to ship to the customer.

- [Narrator] The idea of using iron oxide as pigment

is as old as history itself.

In fact, it was used to record history

as far back as 17,000 years ago.

[gentle music]

Today, iron oxide paintings still endure

in France's renowned Lascaux cave.

The basic concept endured for centuries as well.

And late medieval and Renaissance artists

used iron oxide pigment

for the rich, warm red and orange colors.

- Everyone from Michelangelo to da Vinci,

to Rembrandt and beyond,

have used iron oxide pigments.

[machinery whirring]

- [Narrator] However, it turns out most of those pigments

end up not on a canvas, but in concrete.

- Most people wouldn't know that concrete is colored.

For instance, the floors you walk on,

the concrete block that are structures,

the pavers that are in our homes,

roof tile on the top of homes.

All of these are concrete applications

that have been colored with iron oxide.

In a year, Rockwood Pigments makes enough iron oxide

that would color concrete

that could cover the state of Texas.

- [Narrator] But your closest encounter

with one of these iron oxide pigments

comes every time you open your wallet.

- We make hundreds of tons of black pigment

that gets used in the color for the US currency.

This black pigment is so concentrated,

it makes millions and millions of bills.

Iron oxide black is used in the ink

that goes on the dollar bill because it doesn't fade,

it's lightfast, durable, and it will last a long time.

[uplifting music]

- [Narrator] Our money may come and go,

but because of iron,

Honest Abe will never fade.

[orchestral music]

In February, 2021,

NASA achieved an incredible goal,

when the rover Perseverance landed on Mars.

Its primary mission is to determine

if evidence can be found

that life once existed on the Red Planet.

But for some scientists,

Mars holds another completely different treasure.

- Mars is covered with rust.

Mars is known as the Red Planet

because of the iron oxides present in the Martian soil.

- There's probably billions of tons of iron on Mars

that would satisfy civilization for hundreds of years,

if not thousands of years.

- [Narrator] - While the Earth's crust is about 5% iron,

the crust of Mars contains about 14%.

This vast resource beckons the futurists and scientists

thinking of ways to mine iron,

should we one day establish colonies on Mars.

- My role as a geologist is to find enough minerals

for us to have a society to live on.

- [Narrator] Some estimate that within the next 50 years,

human colonies may be established on Mars,

where mining would be a breeze

compared to the process on Earth.

- On Earth, for us to get to the iron,

we have to create these gigantic open pits

that you see in front of us,

where they go down hundreds of feet just to get to the iron,

and they cover hundreds of square miles in the end.

Whereas on Mars,

all of the iron ore is sitting right on top of the surface.

And although it covers hundreds of square miles,

we don't have to dig down very deep, maybe about 18 inches.

So that's a lot different

than what you see in front of us here.

[intense music]

- [Narrator] The Martian surface may prove

to be even more user-friendly than imagined.

The pictures sent back from various Mars rover missions

suggest that natural processes have already accomplished

a key part of the mining.

- When the probe landed on the Mars surface

and started roaming around,

they started noticing all these little round pellets

and they were wondering, "What in the world is that?"

And they discovered that they was actually iron minerals.

- [Narrator] Scientists believe those pellets

contain amounts of iron similar to the manmade pellets

that need to be mined, crushed, and baked here on Earth.

- What's really good about the iron ore deposits out on Mars

is they're already in pellets

and we can go ahead and put them in the blast furnace.

[frantic music]

- [Narrator] Martian mining offers one further advantage

over Earth.

- Gravity on Mars is about 38% of what it is on Earth,

so everything is a lot lighter.

We don't need the big heavy machinery

because everything is on the surface.

All we have to do is just scoop up the iron minerals

and transport the iron minerals to our community

where we'll convert it into iron metal.

- [Narrator] The iron mine would be refined on Mars itself

to help build the infrastructure

of extraterrestrial colonies on Mars, and beyond.

- So we want to find it on Mars and use it there.

And once we start manufacturing the products,

then we can take it into the other heavenly bodies.

This is like a way station

for our expansion of our people into space.

[gentle music]

- [Narrator] As rich as the treasure of iron on Mars is,

the true mother lode is on asteroids.

Some scientists believe they're comprised of up to 98% iron.

- And these asteroids are so big

that they actually have more iron

than we've ever produced on planet Earth.

[upbeat music]

- [Narrator] Only time will tell

if dreams of mining this essential metal in the heavens

will come true.

But even if our only source remains here on Earth,

our need for iron promises to endure as long as we do.

- We'll always have iron.

Iron will always be a central part of our lives.

It's part of our structures.

It's part of our motion.

It's part of us.

We'll never be without iron.

[iron clanging]