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Duration:08:33
Uploaded:2017-11-30
Last sync:2022-12-26 00:00
It's a GLOW ROCK DANCE PARTY! This video is best watched in the dark! p.s. I've never actually been to a real dance party and had to Google "what are raves like" - turns out they're nothing like this, which is too bad, because this video was a ton of fun to make
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In this video we explore the special properties of fluorescent and phosphorescent minerals to learn how and why they 'glow' under UV light ('black light').

Thanks to Jim for all of his help with this video! And thanks to my sister Serri Graslie for helping with the posters. Did you know you can make signs that also glow under black light (uv light) by using regular ol' highlighters and white poster board?! Sharpie makes a 'Neon' color pack that works, too! This isn't an ad, I just thought it was really cool, and it could be a great activity in the classroom or for learning/playing at home.

ALSO NOT AN AD: To capture the phosphorescence of minerals under shortwave UV light - and film it in complete darkness - we rented a Sony A7s. Technology is ~*magical*~
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Producer, Writer, Creator, Host:
Emily Graslie

Producer, Camera:
Sheheryar Ahsan

Director, Editor, Producer, Graphics:
Brandon Brungard

Interviews with:
James Holstein, Collections Manager - Geology

Production Assistant:
Serri Graslie
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This episode is filmed at and supported by The Field Museum in Chicago, Illinois.
http://www.fieldmuseum.org
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[Emily] Hey, Jim! [Jim] Oh, hi Emily! [E] What are we looking at today? [J] We're looking at some very special minerals. [E] Really?

What makes these minerals so great? [J] Wanna know? [E] Yeah. [J] These minerals are... [Both] GLOW ROCKS!!! [J] Fluorescent mineral dance party! Oh yeah [E] Yeah!

Woo! [E] All right, Jim what actually are we talking about today? [J] We're talking about rocks and minerals that glow or change color under UV light. They display a characteristic called fluorescence. [E] What is fluorescence, Jim? [J] Well, since you asked, fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. [E] Oh boy! [J] All energy is on a spectrum. And what everyone is familiar with, is the visible light spectrum. :O (gasp) Which you have right here!

So, all light is broken down to various colors from red to violet. And when you get to the violet end of the visible color spectrum, you have increasing energy. But when you get off of the visible color spectrum, you go into the ultraviolet range.

So, specifically UV radiation is going into the crystal matrix, the chemical matrix of the chemical compound of these minerals. And there are elements in there called activator elements. And these are trace elements that are part of the crystal structure that are affected by UV radiation.

So, what is the atom made out of? [E] A nucleus. [J] Nucleus with neutrons and protons, and around that are electrons. So when you're pumping in higher energy UV light or UV radiation, that puts more energy into the electrons, allowing them to go to a higher orbit. And when they go back down to the lower levels, so a more stable orbit, they release energy in the form of visible light, at a different wavelength than in visible light.

So let's look at a few, and see what they look like under visible light and UV light. This is a mineral called calcite (CaC03), and lets bring it up to the light (normal white light). What color is it now? [E] Well it-it's colorless. [J] It's kind of colorless.

Calcite is made out of calcium, carbon and oxygen. It's a very common mineral, sometimes you have other elements getting into the crystal matrix, and these activator elements are what causes a color change from colorless to... [E] Pink! [J] Super hot pink. [E] And so what are the activator elements in this one? So, the most common activator element in this is manganese. [E] And that's what is actually fluorescing pink? [J] And that is what's actually fluorescing pink. [E] Wow! [J] Calcite's one of those minerals that can fluoresce in different colors.

So, it's not always the best technique using UV light to identify minerals. If it has different activator elements within the chemical compound, it'll fluoresce different colors. [E] I have been poking this specimen all day long (different specimen). I can't get over how shiny it is, and how boring it looks under regular light. [J] Let's look at it under the regular light, first. [E] Okay. [J] So this is a mineral or, a mineraloid, called opal, okay?

And you've heard of opal it makes makes great jewelry. It doesn't crystallize in the same way it doesn't have crystals these are actually from a silica liquid that forms and cracks and solidifies. And so this one goes from a Gouda color (white light) to (UV light) this really cool green color. [E] that's so pretty.

I love how shiny it is. [J] So Emily. [E] Yes. [J] We talked about how UV light isn't always the best way to determine what type of mineral it is. That's partly because of the activator elements within them, but sometimes it's about the amount of energy that goes inside of it. So we'll take a specimen, and it will look one color under one wavelength of UV light, but we add a different wavelength to it or we put it under a different wavelength it's going to change colors. [E] So you're exposing it to even more energy, it's still in the UV spectrum, but it's a more energetic UV. [J] Exactly.

Electron dance party. [E] Yeah. [J] All right, let's do this thing. [E] Well, Jim. I can't say I've ever filmed in the dark before. [J] Wait till you see what we're gonna see next, we're gonna put on this shortwave UV light and we're gonna see a lot of magic happen. [E] Okay. [J] Let's do this thing. [E] All right. Wow!

What is happening? [J] So this is putting more energy into the minerals. [E] So the minerals are super excited, so they're the elements the electron in the atoms are super excited. And they're dancing more, going up and down and emitting a lot more energy, emitting a different wavelength back. You'll see this calcite specimen we looked at earlier was pink on the longwave.

But on the shortwave it changes to orange. And some of these they have two different types of minerals, these rocks. So you have [E] What's happening in this one? [J] Calcite and Willemite are two different types of fluorescent minerals. [E] And which one is which? [J] Calcites the orange and Willemite is the green. [E] Wow. [J] So much more vibrant colors.

Much more detail. You can see different fluorescent minerals in there. [E] Yeah, that one is purple and brown and green. Wow. [J] Are you down with florescent minerals yet? [E] I'm super down with florescent minerals. [J] Let's move on to the next subject. [E] Okay. [J] So we've been talking about fluorescence up until now.

Let's talk about a different process called phosphorescence. [E] What's phosphorescence? [J] Funny you should ask, it is a process in which energy absorbed by a substance is released relatively slowly in the form of light. [E] Cool. [[J] It's a similar process, in which you have higher energy going into the system in the form of UV light, even visible light sometimes, exciting atoms, exciting the electrons within the atoms. Those electrons jump to a higher orbit and drop back down, like what happens in fluorescence. But the difference in phosphorescence is those atoms or those electrons, stay in the higher orbit a little bit longer and release that energy a little bit more slowly. [E] They hang out at the electron dance party. [J] They hang out after hours.

Anyway, so this is a mineral that displays phosphorescence, it's not a chemical reaction. It's still interacting with UV energy, so when you hit this with a UV light, it'll hold it, and we'll cut the lights out in the room, and you'll see it glowing and the glow would slowly fade away. [E] Okay. [J] Let's try it. [E] So here we are, again, in the dark. [J] Yep. Best way to see these [E] Okay.

And how long should I hold it on there. [J] Not very long at all, you can take it off whenever you want. We'll watch the glow fade... [E] Wow! And it's dark, do it again. [E] Okay, all right.

I'm gonna turn the flashlight off this time. Where's the button? Okay, all right. [J] Ready? [E] Ready. [J] One, two, three.

Off. [E] Whoa. And that's all those electrons hanging out. [J] Just hanging out. Taking their time in the outer shells while they go into a more stable state. [E] Wow, that's so amazing. [J] So this rock has two minerals.

That are fluorescent. One of which is actually phosphorescent as well. [E] Wow. [J] So we have it under shortwave UV light and when we turn off the light, we'll see what glows. [E] Whoa, it's like it's like a star. [J] It's a green Milky Way. [E] Yeah, wow it really glows for a long time. [J] Let me try it one more time to see what it looks like. Absorbing the energy, electrons are dancing about. [E] So happy at this dance party. [J] And then the party ends, we'll see who stays at the party. [E] Wow.

The little green bits [J} Little green bits. Little green dudes. [E] It's so bright. [J] So what'd you think Emily? [E] Jim, this was one of the coolest videos I think we've ever done. [J] Rocks are really interesting and when they do interesting stuff like glow like this. There's so much fun. [E] Yeah, I've learned a lot today.

So thank you for taking the time. [J] So until next time Emily? [E] All right. *high five* *disappears* "It still has brains on it..." - Emily