Secretly Incredibly Fascinating - Gypsum

Episode Date: June 8, 2026

Alex Schmidt and Katie Goldin explore why gypsum is secretly incredibly fascinating. Visit http://sifpod.fun/ for research sources and for this week's bonus episode. Come hang out with us on the SIF Discord: https://discord.gg/wbR96nsGg5 Visit http://sifpod.store/ to get shirts and posters celebrating the show. Help support this show and unlock bonus content! Become a member at https://maximumfun.org/joinsifpod

Gypsum. Known for being a mineral. Famous for, arguably not famous. Nobody thinks much about it, so let's have some fun. Let's find out why gypsum is secretly incredibly fascinating. Folks, hey there, Cipelopods. Welcome to a whole new podcast episode, a podcast all about why being alive is more interesting than people think it is.

My name is Alex Schmidt, and I'm not alone. I'm joined by my co-host, Katie Golden, Katie. Yes. What is your relationship to or opinion of gypsum? Nope. I don't have one. None. This time you got me on this one. I don't, I don't know anything about it at all, literally. This is like, I know it's like a rock. And that's where I meant. That's as far as I got. This is such a cool SIF topic. And thank you to Zed Frank. I'm the Discord for suggesting it. Lots of folks for supporting it. because it is something people have heard of and we're all limited to it's a rock.

And maybe some people not even there. So we'll do a lot of laying out what this is at the beginning. And it turns out it's a whole bunch of things in a way, even though it's just one kind of mineral. It's wild. I never would have picked this topic. And I love when it's a topic that I end up really excited about from researching. I really like these photos you sent me. Like some of them are super pretty.

Also a little bit like disconcerting. I don't know. It's kind of an uncanny valley of like this is a mineral, but some of them look sort of like weird dog toenails. And I don't love that so much. But, you know, it's cool. That's cool. I always send Katie pictures before we tape. This was just a set of pictures of various gypsum crystals.

Yeah. Yeah. I was really a crystal boy this week. You know, usually I'm sending her my crystals anyway. Yeah. This time it was for the show. Yeah. He's always sending me crystals and saying like, you know, hey, like, here's your weekly crystal vibes chakras.

I don't know. I don't really know. I shouldn't even talk about this stuff. I don't know. The first picture is like kind of giving me a little bit of, remember David Bowie Codpiece Labyrinth, the movie? Oh, yes. There's like she falls. what's her name falls down?

Well, Jennifer Connelly, but I think she's called Sarah or something. Yeah, Jennifer Conley falls down a chasm and there's like a bunch of hands in the wall. And that one, it's like, it's giving me that. Like it's kind of claustrophobic in a little bit of an upsetting way. So I'm excited to learn about this because I literally don't know anything about this other than the pictures you sent me in that it's some kind of rocky crystal thing. Yeah, it is a rock that truly all of us deal with every day. And we don't really know it. Really?

And let's get into what it is. Because, yeah, these pictures I sent Katie will be in the Instagram Carousel and also will link them and we'll talk about them right away. Because on every episode, we lead to a quick set of fascinating numbers and statistics. This week, that's in a segment called, I really want to stats you. Really want to stats with you. do do really want to count you Lord but it takes such stats my Lord Nice everyone practice safe stats Thank you to Harry for suggesting that it's based on my sweet lord by George Harrison

But I think it sounded more sexual where I put the word stats He wants to see the Lord but I made it sound different by mistake Yeah it did it did a little bit just a little bit Yeah This is a family friendly podcast Alex Alexander. Yeah. We have a new neighbor

this segment every week. Please make them as silly and wacky as possible. Submit through Discord or to siphot at gmail.com. And the first number is about one of the main pictures I sent Katie. It's about probably the biggest

gypsum crystals in the world. The number is nearly 12 meters long and one meter wide. That's the size of many gypsum crystals in a cave in northern Mexico. we'll link pictures. The article calls them bigger than telephone poles. And that kind of undersells it because there's so much thicker and wider than a telephone pole. They look kind of organic in a weird way where they look like tree things, but white and, yeah, like dog toenails in a way, which I already

said, and I don't like that I keep saying it. Cat Claw's toenails have this kind of color, too, like this milky, whiteish, pearly sort of thing. And not all gypsum is even that color. But we'll come back to this Mexican cave. One source this week is Chemical and Engineering News as the magazine of the American Chemical Society. And they say miners stumbled across this cave recently. It was in the year 2000,

in a project mining for lead and for zinc and especially for silver. But this mine in Naika in the Mexican state of Chihuahua in northern Mexico, they accidentally found the biggest gypsum in the world, almost 300 meters underground. It doesn't look real. Like this looks like the set to a movie, like a Star Wars. You know, it looks like a Star Wars. Yeah, it looks like some, like George Lucas is always like, what if a planet was one thing we haven't done yet?

And the idea would be what if it was these weird rocks? Yeah. What if it was weird rock planet? Or what if it was potato planet? There's just every planet has one thing it does. Oh, I can't wait to go to Potato Planet. And the next number is at least five, because there are at least five different kinds of gypsum crystals that humans have prized across history.

We'll talk about the chemistry in a sec. Chipsum is just one kind of mineral, but it crystallizes in a bunch of different ways depending on the conditions it's in. That tracks to me. That's how I understand crystals to be, like salt. can form different types of crystals. Yeah, and gypsum, a lot of its chemistry is a salt in the chemical sense. It's not an ACL table salt.

Right. But yeah, the kind we're looking at that's gigantic in Mexican caves is a kind that's all over the place in smaller sizes too. I found pronunciations of either selenite or selenite. Selenite makes a little more sense to me because it gets its name from a Greek word for the moon, like selene. And so it's called that because it looks like a big beam of moonlight, this kind of crystal. So I watch ASMR to help me with my sleepy weepies.

And I have, for whatever reason, I'll be honest, like I don't at all subscribe to crystal healing stuff. I'm very cynical. I don't think it works at all. Same, yeah. But gosh darn it, if videos of like crystal mommy's sort of like waving. Solonite in your face, don't just set me right to sleep. Something about that. Yeah.

Yeah. And I feel like crystal people, if you are a crystal person, that's fine. But I really just never think about them because it's such a harmless thing that people are into, right? Like, it's probably not real if it is real great. But either way, it's not hurting anybody to carry gypsum. It doesn't hurt you or anything. When you say crystal people, you make it sound, though, like they're like people, crystalline organisms.

like, you know, no offense to the crystal people out there, crystal-based lifeworms. But the, yeah, no, I mean, like, but it's like, it has a really interesting sound because I, I have watched videos of people just sort of like tapping Solonite together, because that's where I'm at with my life right now. And it's, it's a nice, it's very nice sound. It's like, I don't know, it's like almost, it sounds kind of like some sort of interesting instrument. I get why people think that it has some kind of like interesting mystical properties, because, yeah, it looks like a beam of moonlight, and it has like this sort of like really interesting

sound that it makes. I've never thought about the sounds any of this makes this so cool. Yeah. And the crystals are very pretty. Like I can see why people are drawn to it. And four other ones to mention. One is a similar crystal called satin sparr, which is sort of like selenite, but a little bit more of a fibrous structure. The selenite's usually more transparent looking. Then across history, there's confusing things where two different minerals have been called alabaster by ancient peoples. And one of them is a white and relatively crystallly compact gypsum formation that's easy to carve. So one of the kinds of alabaster is gypsum. Is sat and spar the same kind of rock that? Because like there's a type of mineral

that you can like use to magnify stuff. stuff in a weird way. Yes, satin spire works as a magnifying glass. Yeah, because it's like got these like tiny, but it's a weird way in which it does it because it's not like a magnifying glass where it's glass where it's like convex or concave and it focuses the light. It's like it has, I think like these like microtubules. It's more like fiber optic cables than the shape of glass, which is really wild.

Yeah, and that forms naturally. Yeah. It's not only humans who can form gypsum into that shape. Just a lot of it is that sort of cable-y-to-be magnifier. Yeah, it's wild. It's so cool. If you ever get a chance to like try that out at like a crystal store, it's fun. Yeah, also with any topic like this, I feel like I am like, I'm glad I'm not a crystal

person, but I also wish I was more of a minerals person. You know what I mean? Like minerals are so cool and I don't think about them very much. I also don't enough think about minerals. That was a weird sentence, but it's true. And like I used to go to the San Diego Fair all the time as a kid, and they had a mineral exhibit. So like once a year, I would think about minerals very intensely because they had a very cool mineral exhibit. Big recommend if they're still doing that.

I hope they are. Oh, yeah, any exhibit like that's amazing. Yeah. And two more crystal types here. There's another one. This sort of like alabaster where across history people have called two different minerals this thing. It's called a desert rose. And gypsum is one of the ways you get a desert rose.

The main reason it happens is that the gypsum crystallizes around grains of sand. So then you get a big kind of varied structure that almost looks like a rose's head and petals and stuff. And it's also colored by the sand being in there. Yeah, I've seen these before. This is crazy because I didn't realize I've interacted with so much gypsum like, because I've seen these and appreciated them. To me it kind of looks like almond slivers that have been artfully arranged. But yeah, it's a rock. Ooh, that's a great comparison.

Yeah. Yeah, and across this whole episode, Jipsum will keep being more and more different things. It's kind of hard to pin down. It's not like a diamond, let's say. Like a diamond, oh, I can imagine a diamond great. And there are other kinds of diamonds. But Gypsum, there's a whole bunch of ways gypsum presents itself. It's really cool.

Right. Yeah. It's sort of like character actor. Wow. Like who is gyps? Which character actor? Like Anthony Hopkins? Like who would gypsum be if they were a person?

Oh, oh. Paul Gypsomati. Paul Gypsomati, that's right. There you go. Yeah. Yeah. And by the way, gypsum, this word we have in English now, it comes from a Greek word that means plaster. Okay.

And also it's unrelated to the racial slur of gypsies. which is based on a false belief about Egyptians. So no one needs to sweat me assigning gypsom someday by his name. It's cool. I'm so glad you brought that up because I was trying to think about how to delicately ask that. I wondered almost immediately when I was researching. I was like, wait a minute. Yeah.

Yeah. And it's all separate. So that's fine. And is it the same? Like, does Egypt also like have the same root then? Egypt and gypsies. Yeah, it's all the same thing. It's just a false belief some Europeans had.

Right. The Romani people were from Egypt. Got it. Yeah. Interesting. It's sort of like the term Indians for Indian Americans or Native Americans. Yeah, exactly. Yeah.

Oh, okay. And yeah, and then the last kind of crystal here, and this is also one I sent Katie a picture of. It's called a gypsum flower is the nickname. This is where you kind of have a series of shapes radiating outward from a central point. It can often look like vines or claws or some kind of reaching sort of. a thing. I'm linking a bunch of examples from the National Speleological Society because they're usually in caves. And also what I sent Katie as an example of the Smithsonian that looks almost like a snake that they kept and found because it's amazing. Yeah, it looks like a tendril.

Well, it's wild because it's sort of, you know, I mean, because crystals grow, right? They are not, they don't grow in the same way that plants do because plants have, you know, cellular division that, causes growth and they have a crystalline structure. But I guess that there is some kind of like parallel structure stuff that goes on. Because yeah, it's very plant-like. Yeah, yeah, it's so neat. And that's not even all the amazing natural forms of gypsum. We're just going to kind of move on.

And the bonus show is about another one where there are gypsum sands in the world. Just like all these kind of tiny particles of gypsum. But otherwise on the ground, it can be big seams of rock. It's one of the most common minerals in the world. The next number is six continents out of six because we've been able to mine gypsum on every continent we've tried to. That's wild. Is there a reason it's so common? Yes. The main reason is that gypsum is usually formed by a past time when seawater evaporated. Huh. Okay.

And that's kind of happened all over the world. Right. Yeah. I mean, there's a lot of sea. and evaporation can happen anywhere. So that makes sense. Yeah. Yeah. And it'll often be in seams of other rocks that also come from that sort of situation. Right.

So it's one of the most common minerals in the world. It can still continue to form. And that also gets us into the basic, basic chemistry of it, which sounds complicated, but I'm just going to break it down into three molecules. Gypsum is one molecule of a kind of salt and then two molecules of water. Okay. So it's also what's called a hydrated mineral. It looks dry and hard and stuff, but it's full of water.

Man, she's hydrated, she's moisturized, and she's thriving. Get ready with me while I crystallize. It's also very soft. The number on the Moes scale of mineral hardness, if folks have heard of the Moes scale of minerals, it's only a little over two on the scale. One is the softest, 10 is the hardest. So gypsum's pretty soft, mostly because a lot of it's water. Like, sure, yeah.

And what's the, is like, are diamonds actually the hardest? Diamonds are a 10, and I don't know if they are truly the hardest mineral that's ever been created. And what's like the softest? The example they usually pull for one is telk. Telk. Oh, like talcum powder. Yeah, that's kind of, I don't know, that's also one where I don't know if talc is. being unfairly treated as the softest mineral in the world that feels like an insult.

But it's the example people pull. You guys are so mean to me. You guys are so mean to just because always called me a powder. And then I'm like, the fact that you stood up for yourself means you're harder. Congratulations. You're a two now. And gypsum shakes its hand and gives it a badge and stuff. Yeah.

Yeah. I mean, a quick Google search says that diamonds are definitely the hard. mineral, but, you know, I don't know if I trust Google anymore because maybe it's sponsored by the diamond lobby. Yeah, that's a big business. Talk is a big business. And a lot of the episode will be about gypsum being a big business, actually. So here we go. Yeah. And so gypsum, it's a hydrated mineral. And the main way it forms is that seawater evaporates and then that water vapor combines with a salt now that it's like loose and the result is this mineral gypsum. And, you know, table salt is one example of what chemists would call a salt.

A salt is a molecule made out of ions that balance each other out. Ions are molecules that have a positive or negative charge and so they come together as a salt or other things to balance that out. So like table salt, the two atoms just balance each other. Right. So it's just anything is a salt if it's balanced in that way? Yes, yeah. And so chemists say that many, many, many things are salts. Right. And in gypsum's case, it's a salt called calcium sulfates. It's one ionized atom of calcium. And then a sulfate is one sulfur and four oxygens all put together and negatively charged.

Okay. And then so that's kind of found in seawater, I would assume. And so that's why the evaporation process can create these minerals? Yeah, it's basically often found in places where seawater has evaporated in the past. Right. So especially if like a whole sea goes away, then you have a giant deposit of gypsum. Hmm. Just up and leaves the sea. The whole sea just is like, all right, I'm done.

I'm out. You seas are all the same. Yeah. Okay. So it's, but then how does the water get? involved because I'm looking at these pictures in, Alex, they don't look very wet. Gotcha. This is basically something where I'm reading a source without totally understanding what it's saying.

One key source is the University of Minnesota. They say that the hydrogen and the water easily forms bonds with the salts. I can't really explain why, but it's just a thing where the makeup of water easily bonds with the specific calcium sulfate salt. So it's pulling hydrogen from the water, essentially? Working it into the structure is what they say. Okay. Of a crystal, yeah.

Right. And then the main reason, really, that humans care about gypsum, beyond it just being all over the earth we're trying to live on, is that gypsum easily gives up or regains the water. You can very easily heat gypsum to evaporate out the water, and then you end up with just the salt as a kind of dry powder. You can very easily add warm water to it and it becomes gypsum again. Whoa.

And because we can do that, we can make plaster. Whoa. That's wild. Plaster is gypsum that we like dried out, then put warm water into it so it's a flexible paste and then we shape it into what we want before it dries. Oh, whoa, that's wild. So like, I think I've, okay, actually I have like heard of sort of gypsum-based walls. Is that what that is?

Yeah. And it's one of our favorite ways to make walls in the world. Yeah. Okay. Cool. Yeah. I like that. There are other uses of gypsum we'll get into as well across the episode, but the biggest one has been construction. And there's also other ways to make

plaster, but because gypsum's all over the place, easy to use, it's pretty safe unless you are mining at and inhaling a bunch of the powder. The miners need to protect themselves. But other than that, it's a great way to make plaster. And we've been doing it for many thousands of years in lots of parts of the world. So if you have a plaster wall, is it most likely gypsum? Yes.

Okay. There's actually two ways gypsum has been a key wall material across a lot of history. And the first one is plaster going back to ancient times. The number there's about 4,000 years ago. That is when people on the Mediterranean island of Crete began building a large city and palace complex at a place they called Nassos. On Nassos, for two reasons, they made almost all of their city and palace out of plaster. Like this huge palace of the ancient world used plaster for walls, floors, columns, door jams, seats, stairs, and more. They did that because Crete has huge gypsum deposits and not enough forests. So they mine the gypsum to build everything, and then the limited forests they had, they used for ships.

So their limited wood, they were like, we got to build both. to go trade with other people and invade. Nasus was arguably the first civilization in Europe, and that and other places for many thousands of years have used plaster as much as they can. And then the other main kind of gypsum walls around us was invented in the United States because drywall is usually made of gypsum.

Okay, okay. I didn't realize. What about the ceilings that you like throw pencils in? Can be because there's also there's a past episode about popcorn ceilings and gypsum is not the main, main aggregate in popcorn ceilings, but it can be. So you can also have a gypsum ceiling that way or just drywall. I'm looking it up. It is gypsum. These ceiling, it's like there are these flat square panels used in ceiling board. And I'm not saying you should throw pencils in them, but you can. Okay. Yeah.

I basically found out that if you're in a modern structural structure, that does not feel like it's made of old things, more likely than not you're surrounded by gypsum. It's fun with a topic where I'm like, does that relate to my life? And then I'm just in gypsum boxes all of the time, unless I'm in my car, I guess. Yeah, I'm in a gypsum box right now. Yeah, most listeners are probably able to reach out and touch some gypsum right now. And this drywall use is like a whole new use of the old material and in a new way, It's not plaster construction where you're wetting it and drying it yourself and so on.

And this is a completely United States invention. The key number is 1894. That is when a U.S. Civil War veteran named Augustine Sackett's. Patented a material he called Sackett Board. He was very proud of it, so he named it after himself. And it's the forerunner of drywall. He kept working on it and also sold the idea to a giant company called the U.S. some corporation. And in the 1910s, they put out what they called sheetrock and then called drywall.

Right. Okay. Sack, it didn't stick as a name, though, apparently. It's too bad. No, we moved on, yeah. It is, I feel like it's just too universal of a product. You can't keep calling it after a guy that easily, you know? Right. So drywall, remind me, is that, it's not the plaster. It's like the panels that you put down onto the wooden frame, correct? It's both at once. Oh. Yeah. Like from the beginning of Sackett's idea, it was a core panel of gypsum plaster, but you make that flat and industrially, and then he just put it between two thick sheets

of paper. And now also there might be additional wood as a frame or something, but it's basically a really solid gypsum that's been heated and flattened. and had some aggregate added to it. And then it's between paper and wood in a way where we aren't like looking directly at the gypsum that much. Right. I see. But it's like panels that they nail down onto the frame of the house.

I've seen people who like drywall, people who like nail in the drywall. It's like a mesmerizing, highly skilled process of like. Yeah. you know, sort of cutting it down to size, nailing it, it's incredible. It really is. And also from its origin, it was seen as cheaper than a traditional plaster wall, where it's just all plaster. Like when we were briefly in Brooklyn, we lived in an old, old apartment building where it was all made a plaster. But especially since after World War II, factories have pumped out huge amounts of drywall. And then after World War II, there was a U.S.

baby boom and the biggest burst of home construction in U.S. history. So the U.S. put drywall everywhere and then globalized it through our overall cultural influence. Important question. Is this the kind of wall that Adam Driver punched a hole in in that marriage story movie? I'm going to look at a picture because I feel like yes. Yeah, the way it like crumpled there and stuff, that seems like drywall stuff. Yeah.

Yeah. He's anti-drywall. Right. That's such an iconic image. The last thing about drywall is that one key source this week is an amazing feature for the Atlantic. It's by writer Hanya Ray. And among many things, she interviewed people at the U.S. Gypsum Corporation, which is still a giant business, like a quarter of its own by Berkshire Hathaway. They make so much drywall for so many people in the country and the world.

and she asked them an amazing question of will we run out of gypsum for the drywall? Oh, wow, yeah. Even though there's a bunch of gypsum on earth, even though it's the most common sulfate mineral in the world. Like, is there a scarcity eventually? Right. I mean, how long does it take for gypsum to form? It takes a lot of time to get a big crystal, yeah. Like the giant ones in that Mexican cave, they think, took about one million years to grow. Well, that's, yeah, it's a little bit of a weight.

So even the small amounts take some time, yeah. And that's an excellent question, right? Because, yeah, we can't probably just rapidly make a bunch more gypsum for ourselves. U.S. Gypsum Corp says they have done the math and run models and, like, thought about this. They wanted to know if we'll run out of gypsum on Earth. And they estimate that at current levels of drywall production, the Earth has 350 more years of gypsum. for the drywall. Huh. That's not like a lot, actually. That's, no. Huh. Yeah. I find it comforting and not. No. It's wild. Yeah. That's not, I mean, we won't have to worry about it our lifetimes, but our great-grandchildren will.

Right. Great-great-grandchildren. Maybe great-great-grandchildren. I might be, depends on when we get those robot bodies going. Yeah, yeah. It depends on our airs and also our robot bodies. brain and jar. There's a lot of variables. Yeah. Yeah. Our hairs. It's the great podcasting fortune. Right. And that interview was in 2016. So that's really like a 350 years after the 2010s. That would put us in the 2360s. And I really enjoyed that they estimated out to the 2360s because that's the fictional setting of Star Trek the next generation and deep sports. Space 9 and Voyager is like that decade and the next decade. No wonder they don't have any drywall walls on the Enterprise.

Yes. Now I think of the Starfleet people as being out of gypsum and drywall, even though they went to other planets. Right. I love it. They did have to have a couple of guys for all of the automatic doors just open and close them, though. Oh, yeah. There's a yeoman back there just pulling it, yeah. Yeah, yeah, yeah.

He's in a Jeffries tube pulling the doors. of course. Yeah, it's an art. It's an artisanal skill. So, I mean, are people concerned about that? Is there? Because I would imagine it's not, it's also, I don't necessarily think I'm cool with the idea of stripping all the gypsum in the world to make drywall until we've run out gypsum. Yeah.

The sense I got from the article is they're not worried. They just thought about it. Oh. And also in thinking about it, they decided it's a few centuries from. Nas problem. Yeah. Who cares? Yeah. We'll be building walls out of, you know, Bitcoin by then.

I also, and I think I'm open to the pitch that we'll just be space mining instead, you know, like get stuff from asteroids. Space mining. Right. Yeah. That's far enough out. That's fine. Nice. That's the pitch I'm giving myself about this.

Or we'll live in plastic spheres. There we go. Yeah. Yeah, yeah. That float and have robot butlers. Yeah, lubricate my jar brain, please, which is my entire body. Lubricate my jar brain. Gross.

Okay, so we're running out of gypsum, but it's not going to be a problem in our lifetime, so who cares? Moving on. Yeah, pretty much. And I guess it's a problem that's been building for thousands of years because the Cretans used up a bunch of it, you know? Nassos. I shouldn't call them. the Cretans, huh? People call them the Minoans, but that's kind of a made-up name based on myth, so I don't know what else to call them. Right. And Cretan, as a sort of like insult,

did come from insulting people from Crete, right? Yeah, vast discrimination against Minotars. Yeah. And there's also, we have one last number that's like a between number, between the stories of ancient Nosos and the post-war United States building with Gypsum. In between those two eras, the city of Paris became a famous producer of gypsum plaster. That's why this stuff can be called plaster of Paris. That's basically the same thing. Oh, okay. Has nothing to do with Paris Hilton?

No, and a lot to do with the city of Paris. Yeah. Okay. It turns out that there were very large. large gypsum mines near Paris. And the number there is the year 1774. 1774 is when more than 100 feet of Paris streets collapsed all at once. Oop. Into former gypsum mining tunnels. Sockre blue.

Yeah, Sochre blue. And that story is our takeaway number one. Paris still saves itself from collapsing into its former gypsum mines, partly by filling the tunnels with dead bodies. Oh, cool. That's so French of them. Yeah, for more than 200 years now, they have been working very hard to prevent a couple of the most popular neighborhoods in Paris

from collapsing into the old gypsum mine tunnels. Hmm, and they're like, what's the best, what's the most durable material we can fill these with? It's dead people? Uh, yeah, like walls, and then what are now the Paris catacombs, where even tourists go to see the deceased, you know? Yeah, those spook me.

Not because of the dead people, that's actually the least of your worries. Like, it's how vast they are and uncharted and you can get super lost. Yeah, I didn't go into them when I went to Paris. Yeah, me neither. Too spooky. Yeah, it seems scary.

Yeah, scary. It turns out it's an amazing city engineering story. Okay. It might be one of the first big story. of a city solving structural problems underneath itself. And this, yeah, it starts in the 1700s the story. Key sources are a feature for J-Store Daily by Alison C. Meyer and a report for Radio France International by Sarah Elsis.

The main problem is in two neighborhoods of modern Paris. They're called Montmarch and Belleville. And they're north of the sand, they're relatively new parts of the city, but they're built where Parisians used to make a living digging up the vast gypsum deposits just north of Paris. Like that's a little bit of why Paris is a city, is that you could mine gypsum there. Right. And when did these gypsum mines were they used? Yeah, they started at least like 800 years ago. Okay.

Because we also don't know exactly how the name Plaster of Paris came about. We just know in general it was because people in Paris mined a bunch of gypsum. made a bunch of plaster, built their city and decorations and all sorts of things with it. One story claims that England's King Henry III, so a Henry way back, he visited France in the 1200s, and then when he came back with stories about the plaster that they make in Paris, English builders and speakers said, okay, plaster of Paris, got it, great. Okay. I only associate it with sort of the stuff you can get at Michaels and do like handprints and stuff

with. Right. There can be so many strengths and types of this plaster. Yeah. Like it can be just for goofs or decorations and it can be a whole home you live in forever. Yeah. And the thing with Paris is they thought they could just mine those hills because who wants to live way uphill when you can just live on the flatland? And then Paris massively expanded for centuries. From the 1200s into the 1600s, it was the most populous city in Europe. And then they built homes, cafes, basilicas up on these hills in what are now, Maltmarch and Belleville. And they thought they were building them on top of totally stable former mining tunnels or they just didn't know what's under them. And then there was a massive disaster in 1774. So about 100 feet of street in Maltmarts

collapses into a former gypsum mine. And you wouldn't know now. Like that's one of the most popular neighborhoods for tourists, especially in Paris, because it's so beautiful and there's this basilica on the hill and it used to be a real disaster site. How quickly did it happen? Did it happen sort of all at once? Or was it sort of a slow sinkhole situation? Apparently all at once, yeah. Oh, that is, that's so scary. Yeah. Just getting swallowed up by the earth all suddenly is, I've seen some videos of sinkholes that rapidly progress and it's such nightmare. fuel. Yes. Yeah. It's really bad to like even think about. And it's the past one. There's no video or pictures. So there's just people's descriptions and imaginations running wild. And yeah, it's a bad time.

Yeah. Well, like how many people were, I would imagine people were killed. Yeah. I couldn't get a casualty figure. But you have to think. Yeah. Yeah. And then also other parts of the city were built on former mines for Harder Stone as well. Like they built stuff like Notre Dame. by quarrying stone near Paris, and then Paris kept growing. And so the French government is led by a very new young king. His name is Louis XVIth. He had become king in 74. And he has not been decapitated for several more years, so he says, what do I do?

Because he's, what do I do with my time that I'm not being decapitated? Oh, so boring. I've been learning a lot about the French Revolution. It's really on my mind. Very young king, Louis XVIth, he appoints one of his architects to be a whole new kind of job. They become France's first ever quarries inspector. And the great news is this guy not only solves the mining tunnel problem, but he solves a second problem in Paris as well. Where to put all these bodies!

Exactly. The ever-growing city of Paris had filled its graveyards and cemeteries. that Louis picked a good guy for this job. His name is Charles Axel Guilomo. And he correctly realizes this is a gigantic job. Because when they make him the person doing the job, they say, first figure out where the tunnels are. We pretty much forgot. We need to learn where they are and then make them structurally stable and so on. And he writes to, it's in his journal that, quote, neither I nor my collaborators will see the end of it. referring to the work. So he says, this has to be a system to last, like, centuries. This isn't just a quick fix, stabilizing what's under Paris. I wonder how many of them ended up in their own tunnels that they were building for dead bodies. That would be cool. He also, the French Revolution comes along and Guillermo is almost executed just because they figure he's a royalist because the king appointed him to a job.

So he is almost killed in the process of doing this. That would be like kind of ironic though if your name is Guillem-O and you got guillotined. So right in his name. I have seen some pictures of the catacombs where they literally like put bones in the walls. Was that partially to strengthen them or is that just because they were bored? It seems like it was mostly to be interesting. Okay. Because what Giam-O says is first we're just going to put up like structural walls.

like walls to simply hold the weight of the tunnel up in as many of these tunnels as we can. And then once we've done enough of that, we will move human remains into the tunnels. Yeah. And including some people they disinterred to make new space in the above ground cemeteries. Okay. But that created a giant set of catacombs under Paris. And a few decades later, 1809, it opens to tourists. There's a new source of revenue for Paris and a new cultural thing.

There's a lot of these little cutesy designs inside the Parisian catacombs where skulls are used in design motifs. And I honestly don't know how I feel about that because I don't know. It feels very haunted to me. Yeah. But then again, like they were technically making good use of space. So there was a little bit of a Marie Kondo. philosophy here, but with bones. I also, I feel like I'm not explaining the French Revolution enough to listeners

you never think about it. Like, Guillermo starts this before the revolution. And then apparently some of the early decor in the catacombs was royal symbols, like the Fleur de Lee. And then once the revolution comes in the 1790s, they start smashing up those decorations. So I feel like the death decorations are almost just an alternative that's apolitical. You know what I mean? Right.

Like the people in the Republic felt like that was the way to decorate rather than anything associated with a political movement or a ruler. Nothing political about a bunch of skulls in sort of stripes. Yeah, it's like calming or centrist or something. Calming. It's really strange. Interesting. We all die. Well, yes.

You know. Except you and me. Brain and jar. Well, yeah, brain and jar. But I mean, they do got to use our skulls for something. I don't think the school's going to fit in the jar, so technically, you know, a vase, maybe a vase, a nice vase. There we go. Yeah, but they both did a bunch of structural stuff that was mainly walls and a bunch of cemetery space saving that was bodies that then became like interesting and gothic in the spooky sense ways of looking at them.

And so in two ways at once they turned former gypsum minds especially. to something amazing for the city that is still a long-term attraction and benefit. That's wild. In contemporary times, I thought, is this just sort of an urban legend, or is this true that, like, people have gone outside of sort of the normal tour routes? Because the tour routes are safe, but if you go sort of beyond the tour routes, I think it's like, it's not easy. I mean, it's Labyrinthian, so it's really hard to navigate, so you can actually die of

exposure if you just kind of get lost in them. So that would make sense because the other thing here is they've never finished stabilizing the former gypsom mines. Yeah. Like apparently for one thing, it took some decades to convince Paris's businessmen to stop mining gypsum. Apparently the workings for mining, it didn't shut all the way down until 1840. And again, that disaster was 1774.

So it took a while. The gypsum reinforcing continues. The New York Times says that in 1975, 1975, a Paris city prefect had to halt all building permits in a section of Montmartre until more reinforcement could be put in until they figured out exactly where some more gypsum tunnels were. Wow. So this just continues to be part of the story of Paris. They aren't necessarily putting more dead people into it, but they're always fixing it.

Right. Okay. I mean, you know, that's somewhat comforting because I wouldn't, I wouldn't want to live in Paris and just be moments away from falling into a big cavern of bones. That's not, you know, like I want to enjoy my croissant without worrying about suddenly falling into a big cavern of bones is what I'm saying. especially i feel like just dumb luck your last words would be so touristy it'd be something like when do they light up the Eiffel tower and that was the last thing she ever said before she fell into the camera bones i love this delicious croissant uh-oh are those bones yeah so thank you gypsum for being so weird and we've explored the world's christmas and Paris collapsing and more. So let's take a quick break before a couple more takeaways about Maine and Canada and Mars. And we're back.

And we have two more takeaways about gypsum. The next one is takeaway number two. Studying gypsum might help us learn what kind of life lived on Mars. Oh, lived. Yeah. So apparently, and you know, this is all theories. The latest theory is that there probably isn't very much life left on Mars. if there's any. But in the past, there was probably more water and more life. And the theory is that if we

properly sample and analyze some gypsum from Mars, we can find out what kind of life it was. Well, so how would, we're sort of talking about probably microbial life, right? Not, you know, dudes with hats, Mars hats and Mars shoes. I did. I just imagined a Martian. but he's like Han Solo in the carbamite. Yeah. Yeah. It's not like that.

Yeah. Some little alien guy sort of like with that looks like, you know the rat hole in that one city that looks like some kind of, I think it was actually a squirrel got like trapped in some concrete. Chicago. Yeah. Chicago. Oh, Chicago. Yeah. Chicago rat hole.

They filled that in, which feels sacrilege. Anyways, we're talking about little aliens. So it's microbes. So how would those get, you know, preserved in gypsum? Excellent question. We have studied gypsum on Earth and found that it is a relatively unique space for some kinds of microbes to live in. And we also find that the gypsum on Earth has traces of the past microbes in a way we can see going back to the formation of that rock. Like if it's thousands of years old, we can see back thousands of years.

And if it's older, we can see back older. And so the theory is this gypsum on Mars, we could do the same thing and see exactly what kind of microbes were there and like identify them and everything. So how does it preserve it? Is it, is that actual microbe in there sort of dead, kept in stasis? Or is it more of a fossil type record? It's more of a fossil and more of a alteration of the structure of the gypsum because it sort of made space or was flesh to make space for. something to live in it. Okay, so like the microbes multiply inside of the gypsum and then they die, and then you have a little record of that. Yeah. And on Earth, we've found some amazing stuff that

way, in particular in a salt flat called Salar de Pajonales, which is in the Atacama Desert in Chile. There's a study published in February 2026. Researchers looked at gypsum there. They found what are called stromatolites, which are basically the physical signs that microbes used to live in the gypsum. And in general, we had learned before that that gypsum is oddly good for specific microbes, especially if they photosynthesize, because it's transparent enough to let enough light in for them to eat that, while also protecting them from other rays like UV rays, protecting them from drying out, and then maybe the microbes get at some of the water, too. You know, it's wild. that there used to be this theory of life starting on earth where it was like the primordial

soup. And the problem with that is that it's, if you have like a big boiling cauldron of water and you're trying to get, say, like, proteins to create a chain that then creates life, it's a little too chaotic and it's hard to imagine how a protein chain, which is relatively delicate, could actually survive this big like chaos environment where it's hot and there's things bonging into each other. So then the more modern kind of theories of the beginning of life on earth usually involve some kind of substrate like either maybe like primordial pizza where it's like on some kind of surface or a primordial baklava where it's some sort of mineral that has layers that

something can kind of be in. So it sounds a lot like these microbes may be being able to survive inside of gypsum layers where they're sort of protected, but they can also feed and multiply. Totally, yeah, especially the layer kind of visual, the Baclava, because they need to be the right distance from the outer exterior of the rock to get enough light, but not too much light and so on. So yeah, yeah, they're sort of a wide layer kind of shape, apparently, the part they're living in. Cool. Doing that, we've been able to find signs going back to the formation of the gypsum of what lived in it in Chile and also a similar thing at another find in Argentina. And then the other thing that helps us is that there's just a lot of gypsum on Mars, to the point that we think that on its own is a pretty clear sign.

There used to be a lot more water on Mars. because it's created by the evaporation of like seawater. Yeah. So we think, you know, there used to be even lakes or seas and they all evaporated. And then now you have this red gypsum planet, you know. Cool. And in 2005, the European Space Agency sent an orbiter called Mars Express, detected gypsum at several locations.

And then in 2013, NASA sent the Curiosity rover, which found a series of gypsum veins in a part of a crater it landed in. It's sampled the rock for the first time in our Martian exploration history. So, like, just the next step would be combine these studies of gypsum on Earth with a new probe or mission to Mars. It doesn't even have to be manned. They can just look at the gypsum the way these scientists looked at Chilean gypsum. Are you sure it wouldn't be to send robots over to dynamite the whole place to build, like, an Elon Musk meme factory? The idea of living in a domed city or bunker that he rules is so harrowing.

That's the worst idea of the world. Great. You mean cool? Some sick meaming that could happen. Yeah. Like I'm running out of oxygen and he's like referencing Starship Troopers or something. You know? Right.

Yeah. Great. He's just got like a, I can't has cheap. Burger Cat going, I can has oxygen and he's laughing so hard because he thinks it's so funny. Yeah, and then making more kids randomly. Like, come on, focus up. Focus up. Yeah.

Anyways, that's very cool, though. It's, you know, I mean, I think that would be neat if we could find some fossils on Mars, some Martian fossils, even if it's just microbes. I really think so too. Like I, especially the specificity of it. Like maybe it's life forms we've never seen before. So that makes them hard to identify. But I like that we could go beyond just, oh, there's probably water. So there's probably life.

Like we might be able to look pretty specifically at what lived there. Yeah. It's cool. We can get some of them rocks back home. Yeah. Look at the drips on Mars. Yeah, we just like haven't sense a mission that would look at that. Right.

That they were all before these studies, you know. So it's exciting. Yeah. And our other takeaway, totally different stuff about history, because takeaway number three, gypsum almost sparked two different wars between Atlantic Canada and the U.S. state of Maine. Oh, boy. And the first one was a problem where Canada, especially Nova Scotia and New Brunswick, they have one of the world's most unique gypsum deposits, and then they tried to smuggle as much of it as possible into Maine.

and then the authorities started shooting at each other. Wait, who was trying to smuggle it? Canadian gypsum, gypsom, gipsom, b-uh, I can't. Saying gypsum miner is hard for me to do. Great news. They called themselves plastermen. Plastermen, that's a lot easier to say, yeah. Yeah.

And they tried to smuggle it into the U.S., yeah. Okay. Which is wild. Yeah, and this is a story from the early 1800s, especially the 1820s, on the 1830s. And key sources are a journal article by historian Elizabeth Mank of the University of New Brunswick, a feature for CBC News by journalist Cassidy Chisholm and digital resources from the Smithsonian. Because Nova Scotia and New Brunswick have massive gypsum deposits,

especially there's a part of Nova Scotia where the gypsum's pushed up to the ground surface and you have plants that thrive living on high gypsum soils in ways they don't to other places. There's big white cliffs of gypsum. some. It's full of it. That sounds beautiful. Yeah, the pictures are gorgeous, I'll link them, especially from the Nova Scotia Nature Trust. And then the thing is, when that was just something that people in Nova Scotia and New Brunswick were mining, they were initially bringing it to all of British North America, so whatever. And then there was an American Revolution. So now there's a national border. Yeah, we did do that. Yeah, we did. And we really haven't listed nearly

all the uses of gypsum. A whole other one is helping with farming. It's essentially a fertilizer if you grind it up and use it to boost soil. The salts in it have calcium and sulfur. Plants can build their cells out of some of that. Jipsum also helps aerate soil. It lowers the pH of soil if it's too acidic. Apparently there's a similar beer brewing use of gypsum to make water less acidic when you're brewing your beer. And then gypsum is a rock. It helps keep the soil in place, not a road quickly. So actually for at least a few centuries, people have ground up gypsum to improve their soil. Okay. A whole other thing. So don't only build drywall out of it. Yeah. And when the American Revolution happened, also the British government that still ran Canada

was not necessarily friends with this new United States. And so both countries end up having a sort of tariff situation. And farmers in what's now the U.S. state of Maine wanted to keep getting the gypsum for fertilizing their fields from what had become a different country. And then, as happens with basically all tariffs in history, people realize they could smuggle and make money instead of paying tariffs to a government. So the plaster miners in Nova Scotia, New Brunswick, starts smuggling it into Maine. Yeah, apparently by the early 1800s, when there's only been a United States,

States for a few decades. Plastermen from Canada were smuggling thousands of tons of gypsum across a body of water called Passamaquoddy Bay into Maine every year. Thousands of tons of gypsum. Okay. Well. And then there was just such large scale smuggling. The government of New Brunswick passed an anti-smuggling law called the Plaster Act and appointed a preventative officer empowered to catch and prosecute Canadian gypsum smugglers. They did that in 1820, and it sparked a local conflict that's nicknamed the Plaster War. Did they just throw plaster at each other? No, they used weapons and everything, actually.

Oh, okay. And it basically didn't become an international war because the Canadians backed off and the Canadians mostly shot at each other. Oh. What happened is the preventative officer recruits a bunch of deputies. He chases smugglers. and initially he starts turning around in Passamaquoddy Bay when he's approximately at the territorial line where he would be going into the U.S. He's like, I'm not empowered to go into the U.S. I'm only a New Brunswick officer.

I feel like a lot of Americans don't know that Maine is not just surrounded by water on the top of it or something because we leave Canada off the map. But the top of Maine's pretty adjacent to a couple Canadian provinces, including New Brunswick. But there is this bay that they're crossing with all the gypsum. And as the preventative officer keeps approaching the U.S. line, people on the U.S. side start trying to shoot him with rifles. At one point, somebody there puts out a reward for killing this guy if they can. Because they figure if we shoot him, then we can't be tried in Canada and we can keep smuggling. So we'll help our Canadian smuggler friends out by killing him. I see.

That sounds not super well advised. But okay. Yeah, and then from there it almost became a bigger international incident because then the preventative officer says, fine, I'm going into U.S. waters and I'll chase Canadian smugglers all the way onto the U.S. land. But the first time he did that, an armed mob of about 60 Americans attacked him with axes and guns. They almost killed one of his deputies before those guys fled. And it only doesn't escalate more because New Brunswick repeals the Plaster Act and gives up and just lets the smuggling happen. Okay. So it's like if Judge Dred ended with them going like, you know what, just make crime legal.

Yes. Basically. They just said, we just won't get the money. That's fine. Yeah. Because Yipson's not evil or whatever and we just won't tax it. And Judge Dred is just like, actually, I'm just one guy and there's like a, have you seen how many guys there are? Yeah.

And then from there, a second. time there's almost an international conflict. This one is bloodless, but both the U.S. and Canadian governments rallied more than 10,000 militia and troops to potentially fight. And the fight was over where the border is on the top of Maine. Oh, probably because there's some delicious gypsum. Yeah, apparently throughout the 1830s after the smuggling thing's done, there's especially American lumbermen and then Canadian gypsum miners, but more so the lumbermen, they keep expanding their operations. And everybody says, hey, we don't totally know where the border is between Maine and Canada. Apparently, in the Treaty of Paris that ended the American Revolution, they just said

the border is in some kind of highlands in the watershed of rivers and did not pin that down. Did they not think to look on the ground for the big red dotted line? Thank you. Yes, Bugs Bunny can saw along it and... Right, exactly. And send Maine out into the Atlantic. Right. This is a, you know, classic, classic method of knowing

where borders are. Right. And so not only are guys harvesting wood and mining gypsum, they're also arguing about what country they're even in. Neither country wants to give up all these resources. By the year 1838, both countries have rallied and funded armies to potentially fight a war in the area of Maine and New Brunswick.

The U.S. General Winfield Scott, who's about to lead the entire army in the Mexican war, is sent up to Maine to be ready. And historians call this the Arrestok War. It was bloodless, but it was like the armies were lined up to fight. And then they only solved it through pretty desperate negotiation of an international treaty to set a border. So like the most consequential game of Rochamble ever? Yeah, yeah. And the one other casualty was gypsum.

Oh. Because it turns out there is a really specific decoration in the legislature of Nova Scotia. The provincial legislature building in Halifax has a lot of plaster decorations because the province is full of gypsum and you can easily make plaster. But the main design choice they made was decorative eagles in the upper corner. of door frames. I mean, cool, sick and cool. Yeah, it rules. And unfortunately, in the 1830s, at least one Nova Scotia legislature said, hey, those are

American symbols in our Canadian building and we're about to go to war. So they went around cutting and smashing the heads off the plaster eagles in the building. Oh, come on. Now, that's, I feel like that's sad. I don't think eagles should just belong to only America. that's, you know, they're cool birds. Especially because we were just talking about Mexico before. That's like Mexico's animal too.

It's on the flag. Don't bald eagles have a range well into Canada? Let me check on that. Oh, we don't talk about that, though. Yeah, we don't talk about that. But yes. Yeah, and the CBC has a really funny feature article about it because apparently two different guys could have been the one who damaged the Eagles,

and they are two guys who are not related to each other who both had the last name Doyle, a legislator named Lawrence O'Connor Doyle, or a lieutenant governor in general named Charles Hastings Doyle. We think one or both of them smashed up the Eagles during the Aristoc War era as an insult to the United States. I see. Yeah, definitely bald eagles are in Canada. I'm looking at the government do Canada, parks dot Canada. So yeah, you know.

Yeah, they're all over this region. Yeah, yeah. But yeah, so apparently I haven't toured it. And this article is only a couple years old. But they say that you can see the defaced eagles in a lot of the Nova Scotia legislature in Halifax. And that's an artifact of gypsum and lumber fighting in the time. That's sad. That's, I feel.

I mean, it's like the level of pettiness is when the U.S. started calling French fries freedom fries. It's like be adults. It is very freedom fries, yes. Yeah. Yeah. It changes nothing. It's like little angry toddler logic. Like, well, I don't want to play with you anymore. So I'm going to smash your bald eagles and call them freedom fries. My eagles, no. My freedom eagles. Wait, that's a great. name. Yay. Freedom Eagles. Folks, that is the main episode for this week. Welcome to the outro with fun features for you, such as help remembering this episode, with a run back through the big takeaways. Takeway number one, Paris continues to save itself from collapsing into its former gypsum

mines, partly by filling the tunnels with dead bodies. It's the Paris catacombs. A lot of them used to be gypsomines. Takeway number two, studying gypsombsom. might help us learn what kind of life lived on Mars. Takeaway number three, gypsum almost sparked two wars between Atlantic Canada and the U.S. state of Maine. And then a lot of the show is in the numbers and stats this week.

Those takeaways are great, but we got into everything from all of the gypsum around you all of the time, whether it's plaster that dates back to ancient times or drywall in modern times. Also the most extraordinary gypsum crystals in the world, the chemistry of the stuff, the weird timeline alignment with Star Trek maybe, and more. Those are the takeaways. Also, I said that's the main episode because there is more secretly incredibly fascinating stuff available to you right now if you support this show at maximum fun.org. Members are the reason this podcast exists. So members get a bonus show every week where we

explore one obviously incredibly fascinating story related to the main episode. This week's bonus topic is the amazing gypsum ecosystem in New Mexico. Visit sifpod.f.fod.fund for that bonus show, for a library of more than 24 dozen other secretly incredibly fascinating bonus shows, and a catalog of all sorts of MaxFund bonus shows. It's special audio. It's just for members. Thank you to everybody who backs this podcast operation. Additional fun things, check out our research sources on this episode's page at Maximumfund.org. Key sources this week include a lot of scientific information about Jepsem from Chemical and Engineering News, which is the magazine of the American

Chemical Society, also the University of Minnesota, the State of Ohio Department of Natural Resources, the U.S. National Park System, also linking to the Greek government's Noso Scientific Committee, which preserves and studies that ancient site, a lot of Mars information from astronomy magazine, from popular mechanics, and of course from NASA, key source for Atlantic Canada, almost going to war with my country is a journal article by historian Elizabeth Manc of the University of New Brunswick, and I leaned on other research journalism

from Canadian broadcasting, Radio France International, J-Store Daily, and more. That page also features resources such as native-land.ca. I'm using those to acknowledge that I recorded this in Lenape Hoking, the traditional land of the Muncie Lenape people

and the Wappinger people, as well as the Mohican people, Skategoke people, and others. Also, Katie taped this in the country of Italy, and I want to acknowledge that in my location and in many other locations in the Americas and elsewhere, native people are very much still here. That feels worth doing on each episode, and you can join the free SIF Discord, where we're sharing stories and resources about native people in life. There was a link in this episode's description to join the Discord. We're also talking about this episode on the Discord, and hey,

would you like a tip on another episode? Because each week I'm finding you something randomly incredibly fascinating by running all the past episode numbers through a random number generator. This week's pick is episode 204. That is about the topic of telephone poles. And one fun fact there, there is an entire park of former telephone pole wood testing in New Jersey that's helped make all telecommunications run better worldwide. So I recommend that episode. I also recommend my co-host Katie Golden's podcast Creature Feature about animals, science, and more. Our theme music is unbroken, unshaven by the Budoz band. Our show logo is by artist Burton Durand.

Special thanks to Chris Sousa for editing this episode. Special thanks to the Beacon Music Factory for taping support. Extra, extra special thanks go to our members. And thank you to all our listeners. I am thrilled to say we will be back next week with more secretly incredibly fascinating. So how about that? Talk to you then. Maximum Fun.

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