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The Viral Cookie Monster Agate and How Agates Form (GeoShort) · PlanetGeo: The Geology Podcast

• 0:03
  SPEAKER_01: Welcome to Planet Geo, the podcast where we talk about our amazing planet, how it works, and why it matters to you.
• 0:13
  SPEAKER_01: Alright, let's do some introductions real quick.
• 0:15
  SPEAKER_01: You are Chris Boyce, a nationally recognized and award-winning Earth science teacher in the great state of Michigan.
• 0:21
  SPEAKER_01: I am Dr.
• 0:21
  SPEAKER_01: Jesse Rymink, a geoscience professor at Penn State, and your former student.
• 0:25
  SPEAKER_01: About 15 or 20 years ago, who's really counting anyways, I remember sitting in your class learning the basics of geoscience from you.
• 0:32
  SPEAKER_01: And this is Planet Geo, a podcast where you and I talk about some amazing aspects of our planet, how it works, and why the geosciences are really important to society.
• 0:41
  SPEAKER_01: Okay, Chris, uh, what are we talking about this week for our Geo Short?
• 0:45
  SPEAKER_01: This is a kind of a fun one.
• 0:46
  SPEAKER_00: It is kind of fun.
• 0:47
  SPEAKER_00: We're so I'm sure everyone has seen the Cookie Monster Agate online.
• 0:54
  SPEAKER_01: And if you if you haven't seen it, we'll throw it on our Instagram.
• 0:57
  SPEAKER_01: So go to Planet Geocast on Instagram and look up that.
• 1:00
  SPEAKER_01: And we'll throw it up there today when we release this episode.
• 1:03
  SPEAKER_01: But this is something that some guy in freaking California found or I don't know, Chris, how many times, how many times has this been shared with you?
• 1:10
  SPEAKER_01: I've got it sent to me at least three times.
• 1:13
  SPEAKER_00: Oh no, I've had it at least 50 times.
• 1:16
  SPEAKER_00: Seriously, I'm not lying, I'm not exaggerating.
• 1:18
  SPEAKER_00: At least 50 times.
• 1:19
  SPEAKER_00: 50 different people sent this to you?
• 1:20
  SPEAKER_00: I've had kids that come up to me and say, Mr.
• 1:23
  SPEAKER_00: Boyce, my mom sent this to me.
• 1:25
  SPEAKER_00: They wanted me to see what you think about this.
• 1:28
  SPEAKER_00: So it's been a non-stop barrage of the Cookie Monster Agate, which is really cool.
• 1:34
  SPEAKER_01: But yeah, it's super cool.
• 1:36
  SPEAKER_01: Mostly it's cool because it gives us a chance to talk about agates.
• 1:39
  SPEAKER_00: That's right.
• 1:40
  SPEAKER_00: We thought it would be a good idea to talk about what an agate is and how agates form, because that's what the cookie monster is.
• 1:47
  SPEAKER_00: It is not a hoax.
• 1:49
  SPEAKER_00: This thing is natural and it's real, and it's gonna end up as a very expensive rock in somebody's collection.
• 1:56
  SPEAKER_01: That's right.
• 1:57
  SPEAKER_01: I'm sure somebody's gonna pay a high price for this now famous Cookie Monster Agate.
• 2:01
  SPEAKER_01: All right, so agate.
• 2:03
  SPEAKER_01: I mean, what are we talking about here?
• 2:05
  SPEAKER_01: How does it form?
• 2:06
  SPEAKER_01: It's a really popular thing amongst mineral collectors.
• 2:09
  SPEAKER_01: I don't know.
• 2:09
  SPEAKER_01: Do you have an agate in your collection, Chris?
• 2:11
  SPEAKER_01: I do actually.
• 2:12
  SPEAKER_00: And I uh it's funny, uh, a lot of people want to give me agates.
• 2:16
  SPEAKER_00: Oh, really?
• 2:17
  SPEAKER_00: Yeah, so I have a fair amount of like really nice agate.
• 2:21
  SPEAKER_00: Agates are something that a lot of people like to put in their offices, interestingly enough.
• 2:25
  SPEAKER_00: And they know how I feel about rocks, and so when they move, they're they know that you're a little bit insane about rocks.
• 2:30
  SPEAKER_00: Is that what you mean?
• 2:31
  SPEAKER_00: Is that what you mean to say?
• 2:33
  SPEAKER_00: That's right.
• 2:33
  SPEAKER_00: That's right.
• 2:34
  SPEAKER_00: So they'll give me these things.
• 2:35
  SPEAKER_00: So I have a lot of agates.
• 2:37
  SPEAKER_00: Now I buy like these picture stands and I just hang the agates on that.
• 2:41
  SPEAKER_00: They're really cool.
• 2:42
  SPEAKER_00: I've got them all over my class.
• 2:43
  SPEAKER_00: So, anyway, what was the question?
• 2:45
  SPEAKER_01: So the question was, do you like agates?
• 2:50
  SPEAKER_01: But I guess we don't get that question.
• 2:52
  SPEAKER_01: I mean, my god.
• 2:53
  SPEAKER_01: I do, I do.
• 2:54
  SPEAKER_01: So an agate, okay.
• 2:55
  SPEAKER_01: I mean, an agate is basically a cavity in a rock that got filled with a a certain mineral, and it often forms these really nice bands.
• 3:04
  SPEAKER_01: It has a little bit of crystals inside.
• 3:05
  SPEAKER_01: There's maybe still, in the case of the Cookie Monster one, there's still a little bit of the cavity left behind where it hasn't been completely filled in.
• 3:12
  SPEAKER_00: And we need to though talk about Jesse, and where does the cavity usually come from?
• 3:16
  SPEAKER_00: Like what kind of rock does this usually form in?
• 3:18
  SPEAKER_01: These are Yeah, so there's many different ways that this can form in.
• 3:22
  SPEAKER_01: Sometimes in volcanic rocks, you'll s have little gaps left behind that are actually where the volcanic gas couldn't escape the magma.
• 3:30
  SPEAKER_01: Go back to our plate tectonics episode.
• 3:32
  SPEAKER_01: We talked about the viscosity of magma.
• 3:35
  SPEAKER_01: And sometimes the gas, the bubbles can't escape from the magma.
• 3:39
  SPEAKER_01: It's too thick.
• 3:40
  SPEAKER_01: It can't get out.
• 3:41
  SPEAKER_01: And so what's left behind is a cavity in the rock.
• 3:44
  SPEAKER_01: Sometimes you get this in sediments, sedimentary rock is buried, and there's some particular mineral that is deposited in there that gets dissolved by groundwater flowing through it, which leaves behind a cavity.
• 3:56
  SPEAKER_01: So you can form little cavities in sedimentary rock by stuff that was there initially when it was deposited and then got dissolved later on by fluids flowing through it.
• 4:04
  SPEAKER_01: And this is very common in the southwest US around the Grand Canyon National Park.
• 4:09
  SPEAKER_01: Uh, there's a lot of these types of cavities in central rock.
• 4:12
  SPEAKER_00: So I want to ask you then, and I'm I'm honestly asking, and you you can cut this if you want.
• 4:18
  SPEAKER_00: Is there a difference between an agate and a geode?
• 4:22
  SPEAKER_01: Yeah, yeah.
• 4:22
  SPEAKER_01: So the the difference between an agate and a geode is I think just the difference in that an agate is a particular type of mineral that's formed within a geode.
• 4:32
  SPEAKER_01: So you can have an uh it has a lot of silica in it, and it has a particular kind of silica in the geode itself.
• 4:39
  SPEAKER_00: So why do you get the rings, Jesse?
• 4:41
  SPEAKER_00: What is this?
• 4:42
  SPEAKER_00: What happens?
• 4:43
  SPEAKER_00: So you have this gas pocket in a lava float, okay?
• 4:46
  SPEAKER_00: Where does the microcrystalline, which is a micro means tiny, right?
• 4:51
  SPEAKER_00: Crystals of quartz, these microscopic crystals of quartz.
• 4:55
  SPEAKER_00: Where do they come from?
• 4:56
  SPEAKER_00: How's this happen?
• 4:57
  SPEAKER_01: Yeah, so I mean it's typically fluid that comes through.
• 5:00
  SPEAKER_01: So it's sort of relatively hot fluid flowing through the rocks deep in the crust, and it has dissolved some silica or some calcium uh from somewhere else, and it's transporting it to into this area, and it flows into this cavity, and suddenly it is oversaturated.
• 5:17
  SPEAKER_01: It wants to precipitate out whatever mineral this might be, this silica rich stuff.
• 5:23
  SPEAKER_01: Uh and it's a very good thing.
• 5:24
  SPEAKER_00: So this has to be a super this has to be a super saturated solution that water that is loaded with quartz, right?
• 5:32
  SPEAKER_00: Dissolved quartz, which you said is silica.
• 5:34
  SPEAKER_01: That's right.
• 5:35
  SPEAKER_00: And and so then it fills the bubble in, right?
• 5:38
  SPEAKER_00: And then you get this kind of jelly-like precipitate of this microcrystalline variety of quartz that precipitates on the cavity walls, right?
• 5:50
  SPEAKER_01: That's right, that's right.
• 5:51
  SPEAKER_01: And so where does the banding then come from, Chris?
• 5:53
  SPEAKER_01: Why do you get these little concentric bands?
• 5:55
  SPEAKER_00: Well, so you get this this jelly-like ooze that happens, and then it slowly hardens and crystallizes into this microcrystalline quartz, and then more water comes in, fills the void again, and it it repeats over and over and over again until it either partially fills or completely fills in that former air bubble in a lava flow.
• 6:17
  SPEAKER_01: That's right.
• 6:17
  SPEAKER_01: And so you get this kind of color variation because there's slight changes in the composition of the fluid, chemical changes in the composition of the fluid that as it flows through it, it kind of forms agate or quartz or calcite, whatever is being deposited in there with slightly different colors or slightly different crystal structures so that it represents different impurities, different chemical compositions within the water because it happens at different times.
• 6:41
  SPEAKER_00: Uh, this is a process that occurs over time.
• 6:44
  SPEAKER_00: Now, it is important too that you know, like the agate forms after the lava flow did, right?
• 6:49
  SPEAKER_00: It has nothing to do with the lava flow itself.
• 6:51
  SPEAKER_00: This happened a totally separate event.
• 6:53
  SPEAKER_00: You had this pocket, and then later on, the agate formed due to water that was super saturated in quartz.
• 7:00
  SPEAKER_01: That's exactly right.
• 7:01
  SPEAKER_01: So it's a much later process.
• 7:03
  SPEAKER_01: And Chris, you and I, we've done a lot of uh rock collecting in areas that are dominated by this kind of fluid alteration, this late-stage fluid things like pegmatites in the Black Hills of South Dakota, right?
• 7:15
  SPEAKER_01: I mean, it it's kind of a similar process to what's forming a lot of economic mineral deposits.
• 7:21
  SPEAKER_01: Fluid flowing through rocks and depositing new minerals in cavities is a really important process for developing mineral deposits, things like aluminum in the Black Hills, where there's you know loads of, or there used to be loads of aluminum mining or gold mining and things like that.
• 7:38
  SPEAKER_01: It's an important geologic process that is represented in this cookie monster agate, right?
• 7:43
  SPEAKER_01: That's kind of ridiculous and a little bit annoying that everybody's showing us.
• 7:47
  SPEAKER_00: I mean, you know, when I first saw it, I'm like, that's not real.
• 7:50
  SPEAKER_00: But it is.
• 7:51
  SPEAKER_00: You know, I looked at it like it took me one second.
• 7:54
  SPEAKER_00: I'm like, hoax.
• 7:56
  SPEAKER_00: Um, but then no, it actually is real, and it's so cool.
• 8:02
  SPEAKER_01: You bring up a really good point because if you go on Etsy or you go on Amazon or whatever, you know, you can find agate bookends or agate, you know, whatever that yeah.
• 8:12
  SPEAKER_01: I mean, Tess and I, you know, we've got like a little Etsy shop where we sell bookends and stuff.
• 8:16
  SPEAKER_01: You go on Etsy and you can find fake agate bookends that are like colored pink or colored blue.
• 8:21
  SPEAKER_01: Yeah, these are the same thing.
• 8:22
  SPEAKER_00: And when you say fake though, yeah, they're dyed, right?
• 8:25
  SPEAKER_00: They're not fake.
• 8:26
  SPEAKER_00: They're just they're agates that are real that were dyed to look these spectacular colors, purple and blue and and pink and exactly.
• 8:34
  SPEAKER_01: Because the agate, the material, is actually fairly porous, so you can kind of let dyes soak into it and it'll porous is like a sponge.
• 8:44
  SPEAKER_01: Exactly.
• 8:45
  SPEAKER_01: It'll kind of absorb the color in there.
• 8:47
  SPEAKER_01: So you take a clear, if you look at this cookie monster thing, you know, go to our Instagram, go to Google, it's it's a lot of like light blue, pale gray, and white.
• 8:55
  SPEAKER_01: That's more the natural color.
• 8:58
  SPEAKER_01: And if you put dye on this thing, you know, it would probably turn whatever blue or pink or red that you added in the dye.
• 9:04
  SPEAKER_00: So it'll soak it up.
• 9:06
  SPEAKER_01: Exactly.
• 9:06
  SPEAKER_01: Yep, exactly.
• 9:07
  SPEAKER_01: So don't buy those those no no, buy the real stuff, you know.
• 9:11
  SPEAKER_01: Exactly.
• 9:12
  SPEAKER_01: Exactly.
• 9:13
  SPEAKER_00: Anyway, that's right.
• 9:14
  SPEAKER_01: That's the Cookie Monster Agate thing.
• 9:17
  SPEAKER_01: Kind of went viral a couple weeks ago, and uh, it's super fun.
• 9:21
  SPEAKER_00: It is it's fun, but it's also really cool too.
• 9:24
  SPEAKER_01: Very cool, very cool stuff.
• 9:26
  SPEAKER_01: All right, with that, take care, everybody.
• 9:28
  SPEAKER_00: Take care of the colour.