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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].