While there are a lot of minerals out there, we humans tend to have some favorites.

And those tend to fall into two basic categories: There are the pretty ones that sparkle or glow. And there are the useful ones, which, thanks to some specific  property of the material, we can use to make our lives easier.

But there’s a rare few,  like this pretty blue rock, that have a foot in both camps. This is sodalite, and it’s found everywhere from the  halls of a British royal’s mansion, to chemical processing plants. And it could even be the key to cleaning  up some of our pollution messes, meaning it could make our world prettier, too. [intro music] In 1901, the Princess of Wales, who would later become Queen Mary, wife of King George V of England, was given a piece of sodalite  from a quarry in Ontario.

It was a colourful mass of  small, royal-blue crystals, with white streaks running through it. The princess was so taken with the stone that she immediately ordered some in  bulk to decorate her palatial home, Marlborough House, in London. The owners named their quarry the  ‘Princess Sodalite Quarry in honor of, or maybe just to simply cash  in on, the royal’s interest.

And while sodalite is valuable  as an ornamental stone, it isn’t actually all that rare. It’s a silicate mineral,  related to quartz and feldspar, but it also contains sodium within its structure, hence the name – sodium, sodalite, you get it. Sodalite forms in a wide range of  igneous and metamorphic settings, typically when there isn’t too much silica around.

Mostly, it’s found as colorful, polycrystalline masses like the ones  from the Princess Sodalite Quarry, but occasionally you can  find individual crystals too. There are some clear or whitish crystals  found near Mount Vesuvius in Italy. And one rare form of sodalite called Hackmanite can even change colour when it’s  exposed to certain kinds of UV light!

It shifts from pink to purple in the sun like those super cool sneakers  I always wanted as a kid. and my mom said no. So sodalite can be pretty in all kinds of ways. But it also has a lot more  going on than just looks, because it’s also a zeolite.

Zeolites are crystalline silicate minerals that have these really tiny pores in them. Like, the size of individual molecules tiny. They’re named after the Greek  word for ‘boiling stone’ because water molecules can sit in those pores and be released when the mineral is heated up, making it look like the rock  itself is, well, boiling.

But the size and arrangement of pores in zeolites also means that they can  act like nanoscopic sieves, made to filter out specific molecules. Which is where they get  their other creative name of… molecular sieves. And sodalite’s crystal structure makes  it the ideal basis for a zeolite.

On the atomic scale, this is how it’s built: First, you’ve got aluminum and silicon atoms that are each bonded to four oxygen atoms making tetrahedra shaped  like triangle-based pyramids. These tetrahedra are then linked to  one another by their corner oxygens, creating a 3D cage-like structure out of pyramids, all joined together at their tips. The shape of that cage is like an octahedron  with all of its points shaved off, leaving it with eight hexagonal  faces, and six square faces, looking kind of like a soccer ball.

These crystal cages have open  spaces inside and between them, where so-called ‘guest’ atoms can hang out. This is what creates the zeolite pores. Sodalite’s signature cages are also found in  plenty of other natural and artificial zeolites.

And yes, zeolites can be DIY’ed in a lab. In fact, these days, the majority  of zeolites are man-made, since chemists can design  different arrangements of cages to create the perfect pore  size for the job at hand. Sodalite cages are among the smallest you can get, at roughly two and a half angstroms across, which is about twice the width of a hydrogen atom.

And depending on how those cages stack together, you can get pores up to 10 or  more angstroms in diameter. The fact that their structures  can be so easily manipulated, as well as the fact that the pores are about the same size of atoms and molecules means that zeolites with sodalite cages have become really valuable  to industrial chemistry. They’re used as ion exchangers in things like water softeners and laundry detergents, trapping calcium and magnesium inside the pores, and preventing them from  precipitating out as limescale.

You can also use them as catalysts  to speed up chemical reactions, like converting ethanol into gasoline. The right size of pore can trap a chosen molecule and hold it in place while  chemical reactions happen to it, like how cutting a dogs nails is easier if there’s a second person  there to hold him still. Same goes with cats it is very hard to clip a cat's nails Speaking of cats, your cat probably  spends a lot of time around zeolites too, since they’re great at absorbing liquids and thus are a common ingredient in kitty litter.

And zeolites are also playing an important role in reducing the human impact on the environment. For instance, some zeolites have been created to selectively absorb methane  from mining emissions. Methane is a particularly potent greenhouse gas, so by removing it we can help to  limit the amount of global warming the planet experiences.

Zeolites might also be key to making  better energy storage solutions. They’re great at holding onto  notoriously lightweight hydrogen atoms, which stops them escaping from  clean hydrogen fuel cells. And they’re being put to use to support  another carbon neutral power source, helping to process radioactive nuclear waste.

In nuclear power plants, spent nuclear fuel can be stored  short-term in storage ponds, which is mostly fine. But some of the fission products are soluble, and if you’re not careful, that contamination can leech out over time. But when zeolites are added into the ponds, the pores trap the fission products, and the powdered material can  be pressed into a solid block, sealing off the pores and  reducing the radioactive hazard. d Not only that, but in the case of rare  but devastating nuclear accidents, zeolites can help with cleanup efforts.

Like, when zeolites were added  into contaminated water and soils after Chernobyl and Fukushima, they reduced the concentration of radioactive  nuclides by up to a thousand times. It’s not often you get a gemstone  that’s both easy on the eye, and the basis for so much of  modern and future industry, but sodalite is one such mineral hero. And Rocks Box subscribers can look forward to receiving their  own piece of industrial beauty… though these pieces are probably  going to look better on your bookshelf than in your litterbox.

Rocks Box subscribers get a sample of every  month’s mineral sent right to their door. Whether you want to sign up or just check  out some of our other mineral merch, you can head over to  Scishow.rocks to learn more. [ outro ]