Thanks to Skill Share for sponsoring this episode of SciShow
As the pun goes, geology rocks —
but it isn’t all about rocks.
Because rocks are usually made of minerals,
and minerals are just plain cool in their
own right.
They have a pretty specific definition, but
for the most part,
minerals are solid compounds and inorganic
elements whose atoms form an orderly, repeating
pattern.
Geologists have managed to identify over 5000
types of them,
and while there’s a huge range of abundances,
more than half of those 5000 are so rare that
they’re found in five or fewer places.
Those rare minerals aren’t things like diamonds
or sapphires, either —
because no offense to your favorite ring,
but those are relatively common.
Instead, they’re things like hazenite and
fingerite.
They’re names that don’t make headlines
all that often, but form in really cool ways.
So this list is our way of celebrating them!
Here are 6 of the world’s rarest, coolest
minerals.
That nobody talks about!
[INTRO]
Okay, I know I mentioned it in the intro,
but let’s get this out of the way:
Despite advertising and pricing to the contrary,
diamonds aren’t rare.
Like, at all.
In industry, they’re used all the time for
their hardness.
And even the fancy, gem-quality ones aren’t
that uncommon —
instead, their rarity is often manufactured
by corporations.
That being said, not all diamond gems are
equal.
They can come in different colors, and some
of those colors actually are really rare in
nature.
Like, you might be familiar with the Hope
Diamond at the Smithsonian
or that massive, blue rock the old lady dropped
into the ocean at the end of Titanic.
And blue diamonds are rare.
But the /really/ special ones are red diamonds.
Most colored diamonds owe their hue to some
kind of chemical impurity in their carbon
lattice.
But in some cases, a diamond’s structure
gets deformed under high pressure, and the
atoms shift around a little bit.
That makes some layers of the lattice reflect
pink light.
And if you get enough of them in a deep enough
color, the diamond will come out red.
Or at least, that’s the leading hypothesis.
Scientists still don’t fully understand
how it works
and there is a chance it might have something
to do with a nitrogen impurity.
Either way, these diamonds are really rare,
and we’ve only found them at a couple of
sites in the world.
Right now, the main mine is in Australia.
It supplies 90% of our pink diamonds, and
a tiny fraction of those earn a “red”
classification from the Gemological Institute
of America.
The mine sold their first proper red, or technically,
their so-called “Fancy Red”, in 1999.
And as of today, only about 30 small, red
diamonds have ever been found.
If you’ve ever browsed through the Tiffany
& Company website,
you might have seen a gemstone called tanzanite.
It’s sometimes advertised as being 1000
times more rare than diamonds.
Back in the 1960s, Tiffany’s became the
first company to sell this stone,
but tanzanite isn’t its real name.
Instead, it’s called blue zoisite.
Now, the mineral zoisite isn’t that rare
by itself.
But the blue variety is.
Its color comes from a vanadium impurity —
in other words, vanadium atoms that got mixed
into its crystal structure.
And the world’s only source for it is a
mining area in the Mereani Hills in Tanzania.
It’s so rare that industry experts estimate
the supply will actually run out in a few
decades.
This supply of tanzanite formed roughly 585
million years ago,
due to tectonic activity that would ultimately
create Africa’s most famous mountain, Mt.
Kilimanjaro.
Basically, the rocks within each tectonic
plate smushed into one another,
and under all that heat and pressure, they
melted, transformed, and grew new crystals.
The exact blend of elements tanzanite is made
of came from a mix of these two tectonic plates,
as well as any particles carried into cracks
by super hot gases.
This is why we haven’t found it anywhere
else.
Also, as if tanzanite weren’t cool enough
just because of how it formed, it has a pretty
unique appearance, too.
It’s pleochroic, which means that its color
can change depending on the angle you shine
light through it.
It happens because vanadium atoms can have
different numbers of electrons, which mean
they can respond to light a little differently.
Rough, untreated tanzanite generally displays
blue, violet, and red or brown coloration.
If you buy tanzanite jewelry in a store, though,
you’ll only see the blue-ish colors.
That’s because the mineral has been heat-treated
to make it all pretty
so some of the vanadium atoms have changed
state and no longer reflect that red light.
Now, gems are pretty and all, but most of
the rare minerals on Earth just aren’t cut
out to be gemstones.
Many are rare because they can only form under
very specific conditions, like combinations
of temperature and pressure
or — in the case of hazenite — in extreme
pH.
Hazenite is only found in Mono Lake, which
is in the middle of the California desert.
Unlike some of the other examples on our list,
it isn’t formed from tectonic plates or
smushed-together rocks.
Instead, it’s made by microbes —
specifically, a group of blue-green algae
called lyngbya .
One group of researchers proposed that, when
the algae die, they release compounds that
contain the element phosphorous.
Then, that combines with oxygen, along with
sodium, potassium, and magnesium in the lake
water.
And under high pH, that ultimately leads to
the formation of hazenite.
These crystals come in radiating clusters,
or “tufts” of long skinny crystals, but
they don’t even reach half a millimeter
long.
And also... they dissolve in water.
Which is another reason they’re really rare.
Some news sources call hazenite microbe poop
but the scientists who discovered the mineral
note that it was found on dried-out or decomposed
microbes.
And I’m pretty sure that’s not quite how
poop works.
Other minerals get their extreme rarity from
being made of a rare element combo.
Ichnusaite, for example, was the first mineral
discovered that includes both molybdenum and
thorium.
And if you know anything about thorium —
yes, that does mean it’s radioactive.
That by itself isn’t that weird, though,
because there are actually quite a few naturally-radioactive
minerals.
Most of them just happen to involve uranium,
not thorium.
Like tanzanite, ichnusaite gets its name from
the only place we can find it
— the island of Sardinia.
actually, the old Greek name for the only
place we can find it.
Geologists are still trying to figure out
exactly how ichnusaite’s ingredients came
together in that exact spot,
but they do have some ideas.
For example, the molybdenum could have come
from the island’s molybdenum-bismuth ore
chemically reacting in high-pH conditions.
And the thorium could have come from impurities
in a type of xenotime
which is another mineral also found on Sardinia.
Then, somehow, they combined.
It’s a puzzle researchers are still solving.
Also, in the spirit of debunking mineral myths,
some places have claimed that only one crystal
of ichnusaite has ever been found, but that
doesn’t seem to be true.
In the paper announcing its discovery
the researchers reference both a “first”
and “other” specimens.
So, minerals can be rare because they only
form in a few spots, because they form under
rare conditions, or because they’re made
of rare elements.
But they can also be labeled as rare because
they’re hard to get to, like bridgmanite.
Bridgmanite is made of elements that are pretty
common in Earth’s crust: magnesium, iron,
silicon, and oxygen.
And they’re in a ratio that isn’t too
rare, either.
But one specific arrangement of these atoms
was hypothesized to only exist deep within
the Earth’s mantle,
where a similar compound breaks down in high
pressure and temperature conditions.
Down there, it’s not found in small quantities,
either.
Estimates suggest it makes up 38% of the Earth’s
entire volume!
Unfortunately, studies that attempted to find
it usually ended in failure, because under
relatively ambient conditions,
the crystal structure tends to rearrange itself
into a random, patternless glass.
But in 2014, we finally found some!
Just, instead of inside the Earth, it was
at the site of a meteorite impact.
When that space rock struck the Earth, it
created huge amounts of pressure and raised
the area’s temperature to roughly 2000°C.
Exactly the conditions needed to make this
mineral.
As a bonus, the sample was also encased inside
layers of /other/ minerals that kept it under
enough pressure to eventually study
— although we’re still waiting to hear
any new results.
Over the course of this episode, we’ve talked
about all kinds of things that can make minerals
rare,
from the elements they’re made of to the
conditions they form under.
And if you’ve been wondering if any mineral
checks all four boxes… the answer is yes.
Some minerals are the height of rarity, and
one of them is fingerite.
Which, all things considered, could probably
use a more impressive name.
Fingerite has only ever been seen near the
summit of the Izalco volcano in El Salvador.
It’s found in fumaroles, or cracks in the
Earth’s surface from which steam and volcanic
gases escape.
And it forms when those volcanic gases sublimate
— or turn directly into a solid —
and chemically bond with one another at just
the right temperature and at just the right
ratio.
The important elements here are vanadium and
copper.
If the ratio of these two is off by just a
little bit, something other than fingerite
forms.
And to make things more complicated, it also
needs a temperature between 100 and 200°C.
But sometimes, it happens, and you get these
tiny, opaque black crystals!
Yeah, despite the name, fingerite doesn’t
look too much like fingers —
it was just named after a guy with the last
name of Finger.
Either way, this stuff is really rare, and
back in the 1980s, scientists had only ever
found a few milligrams of this stuff.
Some of it is because of the specific conditions
it forms under, and also because nobody wants
to climb around on an active volcano.
But fingerite also dissolves in water, so
any time it rains, there goes your sample.
With as hard as these minerals can be to find,
it seems kind of weird that scientists would
devote so much time to searching for them.
Like, some of them aren’t even that aesthetically
pleasing.
And you’re not gonna make a ring out of
fingerite because if you get your hands wet,
it will just dissolve.
But there is a good reason for it: Minerals
like these help us better understand the diversity
of our planet.
Unlike the other rocky planets in our solar
system,
Earth has an incredibly complicated variety
of minerals.
And maybe some of them are related to properties
that allow our home to support life.
You know, as long as you’re not living inside
a crack on an active volcano.
Or on top of somewhere a bit too radioactive.
Basically, don’t live everywhere the rare
minerals are, okay?
One of the coolest things about these minerals
is that some of them only last for moment
—
like before a rainstorm.
That’s why the pictures geologists take
of them are so important.
If nobody ever photographed things like hazenite,
only a few people in the world would know
what they look like —
as opposed to all of you who just watched
this video.
But thankfully, there are great photographers
out there.
And if you want to brush up on your photo-taking
skills to help share your discoveries and
memories,
you can try a class from Skillshare.
There’s one called Fundamentals of DSLR
Photography that’s really helpful if you
want to learn what all of those buttons and
dials on your camera do —
or if you already know the basics and want
to learn more.
It’s taught by Justin Bridges, a photographer
out of New York City who’s great at sharing
and capturing the scenes around him.
Skillshare also has more than 25,000 other
courses about everything from finance to music
so there’s a lot to explore.
And right now, Skillshare is offering 500
SciShow viewers two months of unlimited access
for free!
You can check out the link in the description
to learn more.
[ outro]
