- I'm Gabriela Farfan, curator of gems
and minerals at the Smithsonian.
Let's answer some questions from the internet.
This is Gem Support.
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@Okoepp asks, "I have a really dumb question
that I'm too scared to ask in class.
What's the difference between rocks and minerals?"
There's nothing in a rock that is not a mineral.
Rocks are actually made up of minerals.
This is called granite.
If you look closely at this rock,
you'll notice that it has grains of different colors.
These are individual crystals of different minerals.
Contained in this granite, are the mineral quartz,
the mineral feldspar, and the mineral biotite
and muscovite, which is also known as mica.
All minerals are crystals by definition.
In this case, this mineral is called quartz.
What is a gem?
A gemstone is a mineral crystal that has been cut
and faceted by an artist, so this would be the natural shape
of a crystal, and it can eventually be cut
and polished into a gemstone.
@JebBlackwater asks, "Question, what's the difference
between rubies, emeralds, sapphires, et cetera?"
Rubies and sapphires are the same exact mineral.
The mineral is called corundum,
and it is made up of aluminum and oxygen.
The only difference between ruby and Sapphire is
that the gem industry designated the color red for rubies.
Every other color of the rainbow is called sapphire.
You also asked about emeralds.
Emerald is a variety of the mineral barrel.
Many minerals get their colors
from different trace element impurities.
This one has chromium 3+ impurities
on a very traced scale,
and this one has iron impurities to make it blue.
@SeamsterHeidi asks,
"What's the most unusual gemstone you've ever heard of?
I need some inspiration."
I have a treat for you.
This is a mineral sodalite.
The variety name is called Hackmanite,
and Hackmanites are very special
because they have a color property called tenebrescence,
which happens when we shine a UV light on it.
You'll see that the stones are now glowing
in orange-yellow color,
and we're gonna charge them up a little bit.
Orange stone is from Mont St. Hilaire,
a very famous mine in Quebec,
and the yellow stone is from Afghanistan.
Okay, let's get the lights back on.
Now look at how the color of these stones has changed.
A tiny bit of sulfur gives it this color effect.
And now, if we add some light to them, they'll go back
to their original colorless versions,
so just reflecting all of the light back to us.
@LiPerezRey asks, "Where does "The Rock" Dwayne Johnson rate
on the Mohs Scale?"
Well, Dwayne "The Rock" Johnson is off the scale
because he's a cool human,
but his bones are actually made of Bio Appetite,
which is a mineral with a Mohs Hardness of five.
The Mohs Hardness Scale is a scale that we use
to compare mineral hardness.
So when I say hardness, I'm actually referring
to the scratch ability of a mineral, not how tough it is.
The mineral talc has a Mohs Hardness scale of one.
At the other extreme
of the Mohs Hardness Scale, diamond is number 10.
The Mohs Hardness Scale is also a Logarithmic Scale,
which means that the difference between one
and two on the scale is 10 times.
So diamond is 10 times 10 times 10 times 10,
and so on times harder than the mineral talc.
The reason why hardness is so important for gemstones
that are used in jewelry is
that something like a diamond is very difficult to scratch.
So if you're wearing it every day in a ring,
it's much less likely to turn dull over time
because it will not build up scratches.
Whereas diamonds are the hardest on the Mohs Hardness Scale,
which means scratch ability.
Jade is the most difficult to break,
so it is the toughest mineral.
@PetePeters21 asks,
"If diamonds are the hardest substance in the world,
how do they cut diamonds?"
In order to cut a diamond, you need to use other diamonds.
They would have to take a rotating plate that we call a lap
and cover it in diamond powder.
They'll start with a very coarse grit of powder,
and eventually, they get to finer
and finer grits to create the polished effect.
This is called the Kimberly Diamond.
It's over 55 carrots in weight
and it originated from South Africa
and was gifted to the Smithsonian in 2019.
This would be a rectangular or emerald cut.
You may also refer to it as a baguette cut,
and it's very special
because most diamonds are cut in a round brilliant shape,
which means that it's very good at disguising flaws.
Light comes into the diamond, bounces around the facets,
and comes back out to your eye.
In this case, the light comes in, it bounces a little bit,
but you can see that there are no flaws in this diamond.
@Sakasci asks, "How is a diamond's purity graded?"
The four Cs, which stands for its color, its clarity,
its cut, and its carrot weight.
There are many gemological institutes
that can actually give your diamond a grade.
They'll look to see if it has any inclusions
or impurities in the diamonds such as another mineral
that's stuck inside of the crystal,
or if it has any other flaws like a crack.
Then they'll look at the color.
When grading colorless diamonds, people tend to prefer
that there not be traces of yellow.
The yellow is due to small amounts
of nitrogen substituting into the carbon structure
of the diamond crystal.
However, if there's a lot of nitrogen in the crystal,
it will turn more of a brilliant-yellow color,
and that's actually considered a good thing.
We call this a fancy-colored diamond.
They'll also look at how much it weighs,
so the carrot weight, which is a fifth of a gram.
They'll also then judge the cut of the stone.
So is it a round brilliant, is it a pear shape?
Is it a marquee's cut, like an eye shape?
A marquee's cut is an interesting cut
that was more popular in the '80s.
@KXNU asks, "Do synthetic slash cultured diamonds
also last forever?"
Synthetic diamonds are chemically
and crystal graphically speaking the same
as naturally formed diamonds,
so they're also number 10 on the Mohs Hardness Scale.
They all have the same optical properties,
the same thermal properties, and conductivity properties.
They were just not formed through geological processes.
They were formed in a laboratory.
Unfortunately, for all of us, diamonds will not last forever
because diamonds are formed
at very high pressures and temperatures.
So at Earth's surface conditions,
they are not the stable form of carbon.
Graphite is the stable mineral at surface conditions,
so millions of years from now, maybe even longer,
your diamonds will turn into graphite.
@BloodiedRoman asks, "Yo,
they made "Minecraft Obsidian" into a real thing."
Sorry to break it to you, but obsidian was there first.
Here is a piece of obsidian
and obsidian is actually natural volcanic glass,
so it's not a mineral
because it does not have a crystal structure.
This obsidian glass has the same chemical composition
to our granite.
They were magmas that formed underneath the surface
of our planet, but this one ended up nucleating
and growing crystals, whereas this one never had the chance.
Obsidian also has an anthropological connection
because it was used by prehistoric humans
because it breaks very easily
and forms these con coital fractures,
which can be very sharp,
and they were used to make arrowheads
and other knives.
@RocksbyK1 asks, "What is the biggest difference
between fool's gold and real gold?"
This is real gold.
Gold is a mineral and it has this beautiful golden color.
In contrast, this is called fool's gold.
The proper name is pyrite,
and it's composed of iron sulfide,
so it's not actually gold at all,
but it also has this beautiful golden luster.
But if we hold them side-by-side, you'll see
that they're actually quite different in color.
They both have the same cubic structure
for their crystal structure.
This one just happened to form more euhedral crystals,
more blocky, obvious crystals.
This one on an atomic scale would still be crystalline.
You just can't see the crystals with your naked eye.
@Caiobbadaro asks, "Do we theoretically know every mineral
in the universe?"
We currently know of over 5,000 mineral species
on our planet today.
As for the whole universe, I cannot say,
but theoretically speaking, we know that the combinations
of different elements in the periodic table could account
for approximately 9,000.
So we still have a ways to go
to keep finding those minerals.
We're gonna need some more mine in the future
to help us look for them.
@BenKing01 asks, "Where do the minerals
in your mobile phone come from?"
There are approximately 65 elements that are necessary
to make your cell phone run.
Many of them are considered to be rare Earth elements
that oftentimes come in what we call critical minerals.
For example, one
of these minerals would be called spodumene,
and this mineral happens to have a lot of lithium in it,
and lithium is going to be very important
for those lithium-ion batteries.
We mine spodumene from rocks called pegmatites,
and pegmatites are really, really great at concentrating
what we call these incompatible elements.
These are elements that are either too small like lithium
or too big like uranium that they don't like
to fit in your average crystal structures.
Pegmatite deposits occur across the globe,
but they tend to be concentrated in places like Brazil.
We even have some pegmatites here in the United States,
up in Maine, or in California.
@The_Inspirasie asks, "What is the most cursed diamond?"
Historically, people love the idea of attaching a curse
or a good story to a famous diamond.
And what more famous diamond than the Hope Diamond,
which resides here at our National Museum
of Natural History.
In the early 1900s, the Hope Diamond was bought
and sold many times,
and all of its owners kept losing their money
and having to sell this diamond.
And its last private owner,
Evalyn Walsh McLean had a rather tragic life
that befall her family and herself.
So this idea of the curse just kept building
and building with the Hope Diamond.
But today, when we think about the Hope Diamond,
we actually think of it as a blessing
because it has become the cornerstone
of our National Gem collection.
@PhilBrown62 asks, "How do crystals form?"
Different minerals require different temperature
or pressure conditions in order
to build their crystals?
They also need some kind of fluid in order
for those necessary ingredients to get to the right place.
Crystals are formed of atoms,
and so, if you have consistent ingredients, in the case
of this amethyst, which is a variety of quartz,
the ingredients would be silicon and oxygen.
The silicon and oxygen atoms will arrange themselves
in a repeating specific pattern.
In this case, it will make a hexagonal crystal system,
and if you keep adding atoms to this tessellation,
you will eventually end up with a crystal that you can see
with the naked eye.
@Lauraopper asks, "Are pearls considered to be minerals
since their origin is organic?"
Pearls are technically not minerals
because they are formed through organic processes,
and part of the definition of a mineral is that it has
to form inorganically.
However, I'm actually a bio-mineralogist,
so I do study minerals that are formed
through biological processes, and in the case of pearls,
what we're looking at is the mineral orgonite
or calcium carbonate.
So what happens is that the organism, in this case,
a pearl oyster naturally forms this layer of nacre
or mother of pearl inside of its shell,
and if a piece of debris gets stuck inside of its organism
as it's living, it becomes irritated
and it tries to cover that
with the same nacre that we call a pearl.
Another example of a biomineral would be your bones.
You are in fact a bio-mineralizing organism
where your bones are made up of Bio Appetite.
Appetite is calcium phosphate,
and it's also formed through geological processes.
@Bracer788 asks, "What does gem mean?"
We say that something is gemmy
when someone could potentially cut a gemstone out of it.
For example, this crystal of barrel, also known
as the variety emerald is very beautiful.
It's rather transparent.
This gemstone could potentially be cut out
of a crystal like this because the crystal is gemmy.
In contrast, this crystal is relatively opaque,
which means it would be very difficult
to cut a gemstone out of this crystal.
@EmmaTheresaJ asks,
"My friend has a moonstone, parentheses, orthoclase ring
that the jeweler told her she can't get wet.
Is this true?
What's behind that crystal graphically slash geochemically,
or is this a myth?"
Moonstone looks something like this.
You can get it wet.
It's not going to be harmed whatsoever.
Now the jeweler might have been confused
with a different thing, which we call opal.
Opals look something like this
and they are also commonly used in jewelry,
but they're not technically minerals.
Opals are mineraloids, which are almost the same
as minerals but they don't have a crystal structure.
Instead, opals are composed of tiny, tiny spheres made out
of silica, and these spheres are packed together.
This means that opals are very porous
and they can easily absorb water.
So if you're going to do your dishes,
maybe take your opal ring off first.
@TiffySniffs asks, "How are geodes formed
and why are they so cool?"
Well, I agree that geodes are very cool.
If you were to walk around in Utah
and pick up a rock that looks something like this,
break it open, you might find that it's hollow inside
and that it formed a geode.
So geodes form when you have an open cavity,
and this allows crystals to grow inside of the space.
This one is likely filled with the mineral called quartz
or Silicon Dioxide.
This would be your most common geode that you would find.
If you're going to crack open geodes, make sure
that you wear your safety glasses.
Safety first. [chuckles]
@Shelbbylynn11 asks,
"Why does turquoise jewelry have to be so expensive?"
Because the gemstones that they're made from are quite rare.
It's very difficult, first of all, for the Earth
to create these amazing minerals
and to form examples of them that are going
to be large enough, pretty enough in order for someone
to want to make jewelry out of them.
The next part would be someone has to mine that stone.
So a miner would go to a mine, such as one in Arizona,
find that turquoise,
then it has to go to a lapidary, which is the person
that actually cuts the stones into a cabochon,
which is a stone that's polished on top
and usually flat on the bottom.
So it makes a dome shape.
And finally, you need a jeweler that's going to take
that gemstone and mount it into a piece of jewelry.
Now, the metal that is used to mount that piece
of jewelry can be quite an expensive
in and of itself, especially if it's something
like gold or platinum.
So together, you form
this rather expensive piece of jewelry.
@Linostrack asks, "Where do rubies even come from?"
It turns out that rubies
or the mineral corundum can be found all around the world.
If you are interested in finding rubies
in the United States, you could even go
to North Carolina to ruby mines.
However, the most precious rubies,
the most sought-after rubies are from Burma.
There is an area of Mogok Burma
that has a huge city made up of many, many thousands
of people where their entire job is
to find rubies in a mountain of marble.
@Tailsnkitty asks, "What are quote 'Blood diamonds?'"
Unfortunately, minerals
and gemstones often hold a lot of value per volume,
which means they're very small,
but they're very, very expensive,
and thus, they have been embroiled in conflicts
and used to trade for weapons,
and oftentimes, can be directly linked
to conflicts and death.
Ethical sourcing is very important.
Currently, there is a process called the Kimberly process,
which can trace the origins of diamond crystals
before they get cut and sold into jewelry.
So if a diamond comes into the United States without
the proper certification from the Kimberly Committee,
they get confiscated by TSA,
and they're actually brought here
to the Smithsonian's National Museum of Natural History
so that they don't get traded out illegally.
@gDegenXPlay asks, "How do you find your gems?"
As the curator of gems and minerals, myself
and my team, go out and scout
for new minerals that have appeared on the market.
Recently, we acquired a crystal
of the mineral called sapphirine,
not sapphire, and it was one of my favorite acquisitions
because it happens to be the largest crystal
of sapphirine in the world,
and it came from a mine in Madagascar.
So those are all the questions we have today.
Thanks for watching Gem and Mineral Support.
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