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The Geology of Copper · 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.
• 0:12
  SPEAKER_00: Trying to put me in the romantic mode and it didn't work.
• 0:27
  SPEAKER_01: You do have a voice for the sort of uh late night DJ, you know what I mean?
• 0:31
  SPEAKER_01: You could easily pull that off, I think.
• 0:33
  SPEAKER_01: Were you uh did you ever do that in college?
• 0:35
  SPEAKER_01: No.
• 0:35
  SPEAKER_01: You were probably a bouncer in college, weren't you?
• 0:38
  SPEAKER_01: Were you a bouncer?
• 0:39
  SPEAKER_01: I actually was.
• 0:39
  SPEAKER_01: I was for a time.
• 0:43
  SPEAKER_00: About three years.
• 0:44
  SPEAKER_00: Yeah, yeah.
• 0:44
  SPEAKER_00: Yeah, there you go.
• 0:45
  SPEAKER_01: Chris Bull eyes.
• 0:47
  SPEAKER_01: He can come, he can grind your stumps, and he can bounce your party for you if you need.
• 0:51
  SPEAKER_01: Man of many talents over there.
• 0:53
  SPEAKER_00: Those days are long gone, my young sage.
• 0:57
  SPEAKER_01: You're the one getting bounced these days.
• 0:59
  SPEAKER_00: Yeah, no kidding.
• 1:00
  SPEAKER_00: Oh, oh, yeah, get this.
• 1:02
  SPEAKER_00: Bella has a new boyfriend.
• 1:03
  SPEAKER_00: Okay.
• 1:04
  SPEAKER_00: And he's a wrestler in college.
• 1:07
  SPEAKER_00: And um, so I was a wrestler in high school.
• 1:10
  SPEAKER_00: And you know, I'm a bigger guy, so of course, you know, meet the young lad, you know.
• 1:14
  SPEAKER_00: And I said, I just I really, you know, and I kind of gripped my teeth and I said, I really want to wrestle you.
• 1:20
  SPEAKER_00: And he looked at me.
• 1:22
  SPEAKER_00: Of course.
• 1:23
  SPEAKER_00: He sizes me up and down, and he looks at my daughter and said, Can I put him on his head?
• 1:32
  SPEAKER_00: I knew right there I wanted nothing to do with this kid.
• 1:36
  SPEAKER_00: Now he would destroy me.
• 1:38
  SPEAKER_00: Can I put him on his head?
• 1:40
  SPEAKER_00: He was not intimidated at all.
• 1:42
  SPEAKER_01: That's a good one.
• 1:43
  SPEAKER_01: Oh, I like that.
• 1:44
  SPEAKER_01: Well done, young man.
• 1:45
  SPEAKER_01: Well done.
• 1:46
  SPEAKER_01: That's one way to impress around the bullheist household is to just go, ah, can I put him on his head?
• 1:54
  SPEAKER_00: It is like, yeah.
• 1:55
  SPEAKER_01: So that's how you get places in the Bullheist household.
• 1:58
  SPEAKER_01: I I appreciate that, Chris.
• 2:00
  SPEAKER_01: I appreciate that about your household.
• 2:01
  SPEAKER_00: What is that that you appreciate?
• 2:02
  SPEAKER_00: I don't understand.
• 2:03
  SPEAKER_00: Trash talk goes a long way, you know.
• 2:05
  SPEAKER_01: You can you can make a lot of headway with a little bit of trash talk in your household.
• 2:09
  SPEAKER_00: I like it.
• 2:10
  SPEAKER_00: Sarcasm, trash, it all goes a long way in the bullheist household.
• 2:13
  SPEAKER_00: And and Jenny usually leads the way.
• 2:15
  SPEAKER_01: Oh, yeah.
• 2:15
  SPEAKER_01: I mean, you're not, you're, you're the worst trash talker in your household by far.
• 2:19
  SPEAKER_01: Um so the so this episode today is this is a difficult one.
• 2:26
  SPEAKER_01: So, you know, this is this is like forewarning for the listener because it's not simple.
• 2:30
  SPEAKER_01: It's not, I don't know, we've struggled with this a little bit.
• 2:33
  SPEAKER_01: Like how to put together kind of a linear, digestible, compelling story around something that's super interesting and super important, right?
• 2:40
  SPEAKER_00: Yeah, it's a hard balance to strike here because you know, our target is Joyce.
• 2:44
  SPEAKER_00: We cannot forget about her.
• 2:46
  SPEAKER_00: And if we get if we get into the weeds too far with the chemistry, then you know, we lose that.
• 2:53
  SPEAKER_00: But also, this is a geology science knowing podcast, so we have to do that too.
• 2:59
  SPEAKER_00: And it like, you know, you made the comment earlier we were talking before we started recording about comparing this to the geology of uranium.
• 3:07
  SPEAKER_00: The the chemistry of uranium is so much simpler in so many respects than copper.
• 3:12
  SPEAKER_00: Copper is a mess.
• 3:13
  SPEAKER_00: And so that's where we're kind of like, where do we draw this line between talking about something that's really, really important and I think also kind of cool and not losing everybody along the way.
• 3:27
  SPEAKER_01: For sure.
• 3:27
  SPEAKER_01: Because it's a super, you know, it's not a linear sort of thing here.
• 3:30
  SPEAKER_01: So maybe we could just set the stage like, why do we care?
• 3:32
  SPEAKER_01: Let's start out with the why is it important in copper.
• 3:34
  SPEAKER_00: Hold on.
• 3:35
  SPEAKER_00: So I know it's in the title, Jesse, but we gotta say this is about the geology of the red metal, the geology of copper.
• 3:43
  SPEAKER_00: That's what this episode's all about.
• 3:45
  SPEAKER_00: And it's such a cool nickname.
• 3:46
  SPEAKER_01: I love that nickname, the red metal.
• 3:48
  SPEAKER_01: I mean, you know, it evokes, I don't know, it's kind of badass, you know.
• 3:52
  SPEAKER_01: It evokes like, I don't know, what's the what's the game of thrones think?
• 3:55
  SPEAKER_01: The red wedding, you know, it evokes something cool, you know, the red metal.
• 3:59
  SPEAKER_00: Um and I do have to say though, Jenny pushed back on this though, Jesse.
• 4:02
  SPEAKER_00: She's like, No, it's not red, Chris.
• 4:05
  SPEAKER_00: And she, you know, when she says my name like that and she says Chris and she emphasizes that I know she's pissed.
• 4:11
  SPEAKER_00: And I'm like, Well, it is though, it's kind of red.
• 4:14
  SPEAKER_00: And she's like, No, it's not Chris, it's copper.
• 4:17
  SPEAKER_00: It's copper colored.
• 4:18
  SPEAKER_01: Okay.
• 4:19
  SPEAKER_01: She loves Jenny's better at trash talking, but also we didn't come up with this nickname, Jenny.
• 4:23
  SPEAKER_01: Chill out.
• 4:24
  SPEAKER_01: Like, it's not our nickname.
• 4:25
  SPEAKER_01: If we named it, you could give us a hard time.
• 4:27
  SPEAKER_01: But everybody calls it this.
• 4:28
  SPEAKER_01: This is also a timely episode because recently copper was just categorized as a critical mineral by the United States Department of Energy.
• 4:36
  SPEAKER_01: It's already classified as critical by the EU, Japan, India, Canada, several other countries as well.
• 4:41
  SPEAKER_01: So it's kind of in this critical minerals conversation.
• 4:44
  SPEAKER_00: Interesting though, to follow up with what you just said.
• 4:47
  SPEAKER_00: It's not classified as a critical mineral by the USGS.
• 4:52
  SPEAKER_01: Yeah.
• 4:52
  SPEAKER_01: That's right.
• 4:53
  SPEAKER_00: You know, yeah.
• 4:54
  SPEAKER_00: What's going on with this?
• 4:56
  SPEAKER_01: You know, it's a super interesting thing, and I think we should I would I'd love to go back and talk to Nadal Nassar or do it again, you know, have a round two with Nadal Nassar and ask him about these.
• 5:05
  SPEAKER_01: We didn't really get into the sort of borderline ones, the ones that maybe are critical or are not are kind of debatably critical.
• 5:12
  SPEAKER_01: The USGS does not list it as critical because the supply chain is more robust, maybe, than some other supply chains.
• 5:20
  SPEAKER_01: But the reason I think that it has come into this conversation, it's a super abundant element.
• 5:26
  SPEAKER_01: We mine it a lot of copper every year, but it's become more important because the future energy needs.
• 5:33
  SPEAKER_01: We just need copper wire.
• 5:35
  SPEAKER_01: We need a ton of copper wire for a whole bunch of different stuff in the economy a decade from now.
• 5:40
  SPEAKER_00: Exactly.
• 5:41
  SPEAKER_00: And we just estimate this.
• 5:42
  SPEAKER_00: That's all we can do, right?
• 5:44
  SPEAKER_00: But we think that within 10 to 15 years, our copper needs just in the United States are gonna double.
• 5:50
  SPEAKER_00: And so it's a you know, consider you know, considering that estimate, it's hard to believe that the USGS still has not classified it as a critical mineral.
• 6:00
  SPEAKER_00: Interesting, interesting point.
• 6:01
  SPEAKER_00: I got no I it's just like it's astounding to me, but Nadal Nassar would know more obviously way more than you and I combined on this.
• 6:10
  SPEAKER_01: So obviously, we're not the decision makers, and we're not giving our opinion on this.
• 6:14
  SPEAKER_01: It's just, you know, this is the way it is.
• 6:15
  SPEAKER_01: It's it's sort of on the margins of being classified as critical.
• 6:18
  SPEAKER_01: But we kind of talked about this with uranium as well.
• 6:21
  SPEAKER_01: It can get a little bit political, some of these things, and we're not weighing in on that aspect of this.
• 6:25
  SPEAKER_01: We're just gonna talk about the geology of copper.
• 6:28
  SPEAKER_01: But I think, Chris, let's put some kind of quick numbers onto why it could be argued that this is critical, that copper is a critical one.
• 6:35
  SPEAKER_01: And this is one kind of impressive stat, I think, that offshore wind turbines, which we talked to Andrew Duell.
• 6:40
  SPEAKER_00: Hold on, hold on.
• 6:41
  SPEAKER_00: Actually, can I frame this a different way, Jesse?
• 6:43
  SPEAKER_00: So I guess I want to ask this question to our listeners before we get into talking about it.
• 6:48
  SPEAKER_00: What's happening?
• 6:49
  SPEAKER_00: What would happen in the next 10 to 15 years that would put double the stress on our copper?
• 6:55
  SPEAKER_00: It's not just population, it's not just homes, right?
• 6:59
  SPEAKER_00: What else could be going on to contribute to this need?
• 7:03
  SPEAKER_01: Yeah, and I think, you know, think about where copper, where do you find copper, right?
• 7:07
  SPEAKER_01: I think most people probably think, oh, you know, the wires in my house are copper, right?
• 7:12
  SPEAKER_01: You strip off some of the wiring, run into your outlet or your lights, and it's copper.
• 7:16
  SPEAKER_01: And that's true.
• 7:17
  SPEAKER_01: We're not building double the amount of houses in the next decade, though, right?
• 7:21
  SPEAKER_01: Like, what are we building more of?
• 7:23
  SPEAKER_01: And we're building more electric motors.
• 7:26
  SPEAKER_01: We're building more things that produce electricity.
• 7:29
  SPEAKER_01: So instead of having one big gas-fired, coal-fired power plant that's generating electricity, we have a whole bunch of windmills out there that are generating electricity.
• 7:38
  SPEAKER_01: And we have a whole bunch of, we talked about this with neodymium.
• 7:41
  SPEAKER_01: To generate a motor, an electric motor, to generate that force.
• 7:45
  SPEAKER_01: We kind of talked about how this works.
• 7:47
  SPEAKER_01: You put a very strong magnet and you spin it around in a copper coil.
• 7:51
  SPEAKER_01: That's what's driving electricity, driving that current and makes things spin.
• 7:55
  SPEAKER_00: And that's exactly what happens on any turbine, whether it's an offshore turbine or these turbines that you see in the middle of farm fields now that are just becoming more and more and more abundant.
• 8:05
  SPEAKER_00: It's amazing actually how this has changed in the last 15 years.
• 8:09
  SPEAKER_00: I see this all the time when I'm driving out west, whether I'm teaching the class during the summer or whether I'm going on my own personal banging around the western mountains.
• 8:19
  SPEAKER_00: It's just amazing.
• 8:20
  SPEAKER_00: Shoot, Jesse.
• 8:21
  SPEAKER_00: I don't know, maybe 15, 20 years ago, it cropped up in Minnesota.
• 8:25
  SPEAKER_00: For the next few years, I'd I'd look forward.
• 8:27
  SPEAKER_00: I'd be like, ah, they're so cool.
• 8:29
  SPEAKER_00: Because I I love, I love, love, love windmills.
• 8:32
  SPEAKER_01: They do look cool.
• 8:33
  SPEAKER_01: Yep.
• 8:33
  SPEAKER_00: They do.
• 8:34
  SPEAKER_00: And now they're so ubiquitous that it's like, ah, whatever.
• 8:38
  SPEAKER_00: You know, they're almost like telephone poles at this point.
• 8:41
  SPEAKER_00: Yeah, just all over there.
• 8:42
  SPEAKER_01: Yeah, I feel the same way.
• 8:43
  SPEAKER_01: I mean, we were just uh there's a big wind farm about an hour east of Pennsylvania, of where I'm in in Pennsylvania.
• 8:48
  SPEAKER_01: And so you can drive through and it's right on the ridgetop.
• 8:50
  SPEAKER_01: They look kind of pretty on the skyline.
• 8:52
  SPEAKER_01: Andrew Dewitt, who we spoke to earlier, he, you know, he does a lot of work for offshore wind farm companies, you know, that are energy companies that are putting big offshore wind turbines out there.
• 9:01
  SPEAKER_01: Offshore wind turbines require eight tons of copper per megawatt of electricity that they generate.
• 9:06
  SPEAKER_00: Well, hold on, let's frame that in terms of like a typical offshore wind turbine is gonna be five megawatts minimum.
• 9:14
  SPEAKER_00: These are the big wind turbines.
• 9:17
  SPEAKER_00: So five megawatts, each megawatt requires eight tons of copper.
• 9:23
  SPEAKER_00: Um, that's a lot, okay?
• 9:25
  SPEAKER_00: I think we can just sum that up.
• 9:27
  SPEAKER_00: Yeah.
• 9:27
  SPEAKER_01: Absolutely.
• 9:28
  SPEAKER_01: And the way that that electricity is generated is just a big, strong neodymium magnet.
• 9:32
  SPEAKER_01: We talked about that earlier, spinning around inside of a copper coil.
• 9:35
  SPEAKER_01: And the copper coil is wound around it, and that's where the electricity is sort of driven through, and that is distributed to the grid downstream.
• 9:43
  SPEAKER_01: And so, you know, that's one reason.
• 9:44
  SPEAKER_01: We need more copper.
• 9:46
  SPEAKER_01: That's one end of the problem, like the demand curve, we need more copper.
• 9:50
  SPEAKER_01: But there's a supply change as well in copper as well.
• 9:55
  SPEAKER_01: What is, I guess, what do I mean by that?
• 9:56
  SPEAKER_01: Or what are we talking about with this sort of supply side problem with the copper?
• 10:01
  SPEAKER_00: Well, what we're able to find now at this point is getting less and less weight percentage copper.
• 10:08
  SPEAKER_00: So we if we think about ores, an ore is a rock that contains enough of a metal to make mining profitable, right?
• 10:15
  SPEAKER_00: We have to extra we have to take the rock and we have to extract the metal out of it to get what we're after.
• 10:21
  SPEAKER_00: And just some numbers to throw at you.
• 10:24
  SPEAKER_00: In 1900, so 125-ish years ago, they averaged 2% copper by weight, these ores, okay, a good ore.
• 10:32
  SPEAKER_00: By the year 2000, they had downgraded down to 1%.
• 10:36
  SPEAKER_00: And now by 2030, in just a few years, they're gonna be about a half a percent by weight copper.
• 10:43
  SPEAKER_00: So that's diminished by a factor of four in terms of where we used to be as we extracted copper.
• 10:49
  SPEAKER_00: So we have to get better at it because it's just really like every resource, Jesse.
• 10:54
  SPEAKER_00: I mean, we're never gonna find these Saudi Arabia oil fields or these Houston oil fields anymore.
• 10:59
  SPEAKER_00: You you know, we're doing things differently, we're doing things more efficiently, and we have to because this is where we're at now in society.
• 11:07
  SPEAKER_01: But we need to crush up four times the amount of rock to get the same amount of copper out of it nowadays.
• 11:12
  SPEAKER_01: And there's a lot of companies being formed to kind of do this more efficiently, both explore more efficiently, actually, and find the stuff that's underneath the surface.
• 11:21
  SPEAKER_01: Like we've kind of walked around the surface of the earth and found a lot of the high-grade deposits on the surface.
• 11:25
  SPEAKER_01: There could be some berry that we don't know about yet, and so there's a bunch of companies sort of tackling this problem in different ways.
• 11:31
  SPEAKER_01: But suffice to say, we need more copper.
• 11:33
  SPEAKER_01: We're gonna need more copper, and we can't find it as easily.
• 11:36
  SPEAKER_00: That's right.
• 11:36
  SPEAKER_00: And I think you touched on a point that we're gonna put a pin in and come back to and talk about at the end of the episode how does copper form?
• 11:43
  SPEAKER_00: How do these copper deposits form?
• 11:45
  SPEAKER_00: Which which I think is important with any geology course to talk about is just from the standpoint of so people know a little bit about how copper forms.
• 11:57
  SPEAKER_00: I kind of liken it maybe to people raising their own cattle for food or whatever like that.
• 12:03
  SPEAKER_00: We need to know where resources come from, and knowing a little bit about how they form and understanding that these processes they take either way too long to count on, you know, as replenishing of supplies, or this is just a finite thing.
• 12:17
  SPEAKER_00: I mean, it one it's going, going, and then it's gone.
• 12:20
  SPEAKER_01: I I agree completely with with you on that one, Chris.
• 12:22
  SPEAKER_01: And I this brings up a good point.
• 12:24
  SPEAKER_01: Recycling is always potentially a solve for some of this, right?
• 12:27
  SPEAKER_01: Like if we get better at recycling copper, that'll help alleviate some of this demand problem that we need.
• 12:33
  SPEAKER_01: You know, we can repurpose it, recycle it, repackage it.
• 12:36
  SPEAKER_01: So that can help a lot.
• 12:37
  SPEAKER_01: Let me just touch on one thing real quick, Chris, before we move into sort of the geology of copper here, is that copper's the oldest, well, one of the first metals that was ever used by humans.
• 12:48
  SPEAKER_01: And it was exploited over 7,000 years ago, which kind of blew my mind that copper was being used a really, really, really long time ago.
• 12:56
  SPEAKER_01: And copper, it's a biologically important element as well.
• 13:00
  SPEAKER_00: And so the human body has Can I interrupt you and ask a question?
• 13:04
  SPEAKER_00: Why what were they using copper for 7,000 years ago?
• 13:08
  SPEAKER_00: Was it the fact that copper can be malleable and can be flattened?
• 13:13
  SPEAKER_00: And were they making tools out of it, or were they using it for maybe cooking because it's such a good conductor of heat as well?
• 13:20
  SPEAKER_01: I think it's you know, a lot of tools, as you said, it can be it's malleable, it can be you know shaped and made into various uh you know hooks and things like that and and weapons.
• 13:30
  SPEAKER_01: I think history has these copper age, bronze age, iron age, all those different ages.
• 13:35
  SPEAKER_01: And copper was the first one.
• 13:36
  SPEAKER_01: Bronze is an alloy of copper with other stuff in it, and so that came later and is a little bit harder, and and so there's all the techniques were were sort of developed to do this.
• 13:46
  SPEAKER_01: But copper was exploited a really long time ago, and we'll talk about Michigan has a bunch of native copper deposits, and up in the upper peninsula of Michigan, copper was used for a very long time, both ceremonially and functionally.
• 13:58
  SPEAKER_01: So it's a really it's a really important element and it's a really cool element, and it can be used to do a whole bunch of stuff.
• 14:04
  SPEAKER_01: So, Chris, is it time to move into the geology of copper and get into some of the basics here?
• 14:09
  SPEAKER_00: I think so.
• 14:10
  SPEAKER_00: I do want to touch upon one thing though that we didn't talk about in terms of the importance of copper.
• 14:16
  SPEAKER_00: It is actually also an important constituent of what's in our blood.
• 14:20
  SPEAKER_00: We have between 1.4 and 2.1 milligrams of copper per kilogram, and a kilogram is like 2.2-ish pounds of our body weight, and it's used in the body.
• 14:31
  SPEAKER_00: You know, the a couple things that are really important about this is one, it bacteria will not grow on copper.
• 14:36
  SPEAKER_00: Now, copper does a lot of other things chemically, you know, it oxidizes and it does a lot of that kind of stuff, which makes it really complicated.
• 14:42
  SPEAKER_00: But copper's really essential to us as humans because it's used to form bone cartilage, tendons, and it forms sheaths around nerves, which is really kind of just fascinating.
• 14:53
  SPEAKER_01: Astonishing, yeah.
• 14:55
  SPEAKER_00: It's also a critical element in the manufacture of hemoglobin that you know that's red blood cells.
• 15:00
  SPEAKER_01: We don't often like to get into too much biology here, but uh it's worth noting when one, you know, one element that we're talking about so important geologically is also quite important biologically as well.
• 15:09
  SPEAKER_00: Maybe Dave and Ron, our dads, will be proud of this episode if they if they listen to it.
• 15:14
  SPEAKER_00: Maybe they'll be this is maybe they'll be proud.
• 15:15
  SPEAKER_01: Joyce will tell us.
• 15:16
  SPEAKER_00: Yeah, that's true.
• 15:18
  SPEAKER_00: She'll send you an email.
• 15:19
  SPEAKER_00: But my if my dad doesn't mention this, if uh you know, within a couple weeks after it is released, then I'm gonna come down on him for like, hey, Dave.
• 15:27
  SPEAKER_00: Yeah, you're gonna know.
• 15:27
  SPEAKER_01: You'll know that he's not an avid listener anymore.
• 15:30
  SPEAKER_00: No, you only have one son that does a podcast, Dave.
• 15:33
  SPEAKER_00: Let's go.
• 15:33
  SPEAKER_01: Yeah, you know, like it's not that hard.
• 15:35
  SPEAKER_01: It's like a half an hour a week.
• 15:36
  SPEAKER_01: Come on.
• 15:36
  SPEAKER_01: All right, Chris.
• 15:37
  SPEAKER_01: Let's get into the geology here.
• 15:38
  SPEAKER_01: And again, this is gonna get a little bit complicated.
• 15:41
  SPEAKER_01: We're we're gonna try and keep it linear so that it's relatively easy to follow along with, but uh, it's a little bit difficult.
• 15:47
  SPEAKER_01: So bear with us here.
• 15:49
  SPEAKER_01: I think Chris, let's go through.
• 15:51
  SPEAKER_00: I think the way we've got it, Jesse, I I think it's it's okay.
• 15:54
  SPEAKER_00: Because really what we're gonna do is just a little bit of chemistry now, and then we're gonna get into the geoscience behind it.
• 16:00
  SPEAKER_00: You know, where where do these things form from a like a tectonic or you know, a geologic setting?
• 16:06
  SPEAKER_00: So I think we're I think we're good.
• 16:07
  SPEAKER_01: Okay, that sounds good.
• 16:08
  SPEAKER_01: So why don't you lead us off?
• 16:09
  SPEAKER_01: And I think one thing to visualize here is how do we often see copper, right?
• 16:13
  SPEAKER_01: We think of copper in copper wire, which is almost pure copper.
• 16:17
  SPEAKER_01: So lead us off into chemistry here.
• 16:20
  SPEAKER_01: What's going on?
• 16:22
  SPEAKER_00: Okay, thanks for throwing me that uh unexpected lob, I guess.
• 16:27
  SPEAKER_00: Uh it's not really a lob, that was a fastball that you just threw at me.
• 16:30
  SPEAKER_00: But um so in a typical chemistry class, you don't get into this kind of bonding very often.
• 16:37
  SPEAKER_00: You talk about covalent bonds, you talk about ionic bonds, and you talk about hydrogen bonds.
• 16:43
  SPEAKER_00: And those are really the three main chemical bonds that that are discussed.
• 16:47
  SPEAKER_00: Metallic bonds are kind of glossed over if they're touched at all, but in geology, they're actually really kind of a an important thing for these native elements like gold, silver, and copper.
• 16:57
  SPEAKER_00: And the reason one of the reasons why they're so dense is it has to do with these valence electrons, these outer shell electrons, right?
• 17:05
  SPEAKER_00: And that's 98% of all chemistry revolves around these valence electrons, these outer shell electrons.
• 17:13
  SPEAKER_00: Absolutely.
• 17:14
  SPEAKER_00: The thing is with these native elements though, gold, copper, and silver, is that those valence electrons they don't belong to any particular atom.
• 17:23
  SPEAKER_00: They're free to float throughout the mass of atoms that are stacked together.
• 17:29
  SPEAKER_00: And because they don't rigidly belong to a particular atom, they're free to come and go, you know, they're free to come out, in, and flow through.
• 17:38
  SPEAKER_00: Well, that's why they're malleable.
• 17:40
  SPEAKER_00: That's why you can pound them flat.
• 17:42
  SPEAKER_00: That's why you can draw them into wire.
• 17:44
  SPEAKER_00: It makes them ductile and malleable and these properties that normal substances you couldn't do that.
• 17:50
  SPEAKER_00: If you smack a normal, you know, silicate mineral like quartz or feldspar, for instance, those electrons are rigidly held in place and they break then.
• 18:00
  SPEAKER_00: And you don't have that with these native elements.
• 18:02
  SPEAKER_00: And so metallic bonding is just kind of a cool thing.
• 18:05
  SPEAKER_01: It's a super important thing because these electrons, as you said, they're free to sort of migrate, which makes them an excellent conductor.
• 18:12
  SPEAKER_01: This is why they conduct electricity so well.
• 18:14
  SPEAKER_01: And so copper is used as a metal in wire because it's malleable, and B, it conducts.
• 18:20
  SPEAKER_01: And so silver is the only metal that's a better conductor than copper.
• 18:24
  SPEAKER_01: You know, we often see copper in wires, so that's what people kind of think about when we think of copper.
• 18:28
  SPEAKER_01: Um, but also, at least we think about copper on roofs or on, you know, some people have them as like rain downspouts or something like that in old homes.
• 18:38
  SPEAKER_01: But also the Statue of Liberty is kind of a it was copper plated.
• 18:42
  SPEAKER_01: And so we often see copper having this greenish, bluish layer of what is usually copper carbonates or copper salts that like weathered copper has this kind of greenish patina to it, I suppose, or this greenish layer on top of it.
• 18:55
  SPEAKER_00: And those copper salts are kind of important with the Statue of Liberty because it's obviously getting sprayed with this kind of sea salt all the time.
• 19:02
  SPEAKER_00: Yeah, absolutely.
• 19:03
  SPEAKER_00: There was one of the things you just kind of glossed over it.
• 19:05
  SPEAKER_00: I just want to make sure.
• 19:06
  SPEAKER_00: So you said that silver is the only metal that's a better conductor, both heat and electricity-wise, than copper is.
• 19:13
  SPEAKER_00: The reason why that's not obviously widely used then, because it's better than copper, is because it's so, so much more rare.
• 19:21
  SPEAKER_00: Or it's way less common, let's say that.
• 19:24
  SPEAKER_00: Right.
• 19:25
  SPEAKER_01: So exactly, exactly right.
• 19:28
  SPEAKER_01: And oh wow, segue award, Chris, because that leads us very nicely into the concentrations of copper.
• 19:33
  SPEAKER_01: Let's just put some numbers through these things.
• 19:35
  SPEAKER_01: Copper, like many of these elements that we've talked about, many of the sort of geology of X element that we've talked about, it gets concentrated into the crust.
• 19:44
  SPEAKER_01: So it kind of occurs on average if you took all of the continental crust, copper is about 50 parts per million.
• 19:49
  SPEAKER_01: We've talked about that parts per million measurement before.
• 19:51
  SPEAKER_01: It's a really, really low concentration.
• 19:54
  SPEAKER_01: One part per million means one atom in a million is going to be copper.
• 19:58
  SPEAKER_01: So this is 50 atoms out of a million will be copper.
• 20:01
  SPEAKER_01: And we talked about this.
• 20:02
  SPEAKER_00: I just want to interject something because you know we talk about parts per million, and my favorite thing then to talk about is the greenhouse gases and things like that.
• 20:10
  SPEAKER_00: And carbon dioxide is the most important greenhouse gas because of its rapid increase in parts per million in our atmosphere.
• 20:18
  SPEAKER_00: Twenty five years ago we were at like 350 parts per million.
• 20:22
  SPEAKER_00: Now we're at 420 plus parts per million.
• 20:25
  SPEAKER_00: That's a significant increase in a relatively short period of time.
• 20:28
  SPEAKER_00: But like you said, it's 425 molecules of carbon dioxide per million molecules of normal air, mostly oxygen and nitrogen.
• 20:38
  SPEAKER_00: So even though we're talking about relatively low concentrations, they can still be exceedingly important.
• 20:44
  SPEAKER_01: Oh, massively important.
• 20:45
  SPEAKER_01: And so we're going to kind of step up in concentration here.
• 20:48
  SPEAKER_01: So we go from just background copper concentration, 50 parts per million, to make it a mineable deposit.
• 20:53
  SPEAKER_01: You kind of touched on this earlier, Chris.
• 20:54
  SPEAKER_01: It used to be about two weight percent copper, 2% of the rock by weight would be copper.
• 21:00
  SPEAKER_01: Now we're we're sort of extractable, economically extractable copper deposits are about half weight percent copper, so 0.5 weight percent copper.
• 21:07
  SPEAKER_01: And that's a relatively small amount compared to other deposits that we've talked about.
• 21:13
  SPEAKER_01: And often it's such a small volume that sometimes we need to take that rock.
• 21:16
  SPEAKER_01: So you crush up, you know, a ton of rock to get a little bit of copper out to get half a weight percent of copper.
• 21:22
  SPEAKER_01: Sometimes that needs to be doubly processed.
• 21:25
  SPEAKER_01: So we need to process it once to concentrate the copper, then process it again to fully extract the copper, just because it's such a low grade.
• 21:32
  SPEAKER_00: That's amazing.
• 21:33
  SPEAKER_00: Well, let's talk now, Jesse, about some of the most common copper-bearing minerals because these are some of my favorite.
• 21:42
  SPEAKER_00: In fact, one of the ones that we're gonna talk about here briefly is my favorite mineral of all time.
• 21:47
  SPEAKER_00: And if you're an avid listener of this show, you should know this.
• 21:51
  SPEAKER_01: It's as you're right.
• 21:52
  SPEAKER_01: No, come on, are you serious?
• 21:54
  SPEAKER_01: It's malachite, it's malachite.
• 21:56
  SPEAKER_01: It's malachite.
• 21:57
  SPEAKER_01: Let's frame it a minute.
• 21:58
  SPEAKER_01: Copper minerals, they're beautiful.
• 22:00
  SPEAKER_01: You're right.
• 22:00
  SPEAKER_01: They are stunningly beautiful.
• 22:02
  SPEAKER_01: But we're like zooming in now, right?
• 22:04
  SPEAKER_01: We're going the rock, the entire rock might have half a percent copper, but there'll be certain minerals in there that contain a lot more copper.
• 22:11
  SPEAKER_01: And so we're going to talk about which minerals are really important for mining copper, which ones contain all of the copper.
• 22:17
  SPEAKER_01: And Chris, have we ever collected azurite and malachite together?
• 22:21
  SPEAKER_01: I don't actually know if we've been if we've gone to a copper deposit before.
• 22:25
  SPEAKER_01: We've spent a lot of time like pegmatites and stuff like that, but not really copper deposits, if memory serves.
• 22:30
  SPEAKER_00: You are correct.
• 22:32
  SPEAKER_00: So we could have done this in the upper peninsula in Michigan, Michigan's upper hand, but we didn't go far enough.
• 22:38
  SPEAKER_00: You have to go far to the west, almost into Wisconsin, then up what's called the Kiwanot Peninsula, and we'll talk about that a little bit later on to get to the copper.
• 22:48
  SPEAKER_00: The part where we have spent the bulk of our time at the UP is in the kind of central, north central part, and that's iron country.
• 22:56
  SPEAKER_00: And we've collected then a lot of our iron minerals there.
• 22:59
  SPEAKER_01: So let me ask you a question then, because you, I mean, this this field trip that you do you still run your geology spring field trip or not?
• 23:07
  SPEAKER_00: So I have not since COVID.
• 23:09
  SPEAKER_00: That's not my question.
• 23:12
  SPEAKER_00: You just add that.
• 23:12
  SPEAKER_00: I know, but I have a I have a better question.
• 23:15
  SPEAKER_01: That is a question.
• 23:16
  SPEAKER_01: That's not the question, though.
• 23:18
  SPEAKER_01: Okay.
• 23:19
  SPEAKER_01: So now are you getting ready for your V.
• 23:22
  SPEAKER_00: Well, can I finish my answer though?
• 23:24
  SPEAKER_00: Sure.
• 23:24
  SPEAKER_00: Because this is important to me.
• 23:25
  SPEAKER_00: I I'm really excited about this.
• 23:27
  SPEAKER_00: I haven't been able to do it since COVID.
• 23:29
  SPEAKER_00: My last trip was 2019 because in the spring of 2020, everything was shut down.
• 23:36
  SPEAKER_00: So 2019, my daughter was actually on the last group that went out, and she was a junior in high school at that time.
• 23:45
  SPEAKER_00: But I have recently decided to not coach track anymore.
• 23:49
  SPEAKER_00: And that's gonna free me up now because it's it was always really, really difficult.
• 23:54
  SPEAKER_00: Now I have permission and now I have time.
• 23:57
  SPEAKER_00: So I am yeah, starting this spring, this coming spring, I will restart.
• 24:02
  SPEAKER_01: This is a really good lead-in then to my actual question.
• 24:05
  SPEAKER_01: The question here is because I remember this trip.
• 24:08
  SPEAKER_01: I went on this trip.
• 24:09
  SPEAKER_01: This was like a very, I don't know, it's etched in my memory.
• 24:12
  SPEAKER_01: This one exercise on this trip where you took, I've talked about it before, where you take us out, and there's this like point out in Lake Superior that's like a basalt flow, it's been metamorphosed, a whole bunch of veins cross-cutting, and you're like, hey, put them in order.
• 24:23
  SPEAKER_01: There's like, I don't know, five generations of veins.
• 24:25
  SPEAKER_01: I'm making that up, but there's a bunch of vein generations, and you're like, put it in order, and it's just a cross-cutting relationships exercise.
• 24:32
  SPEAKER_01: That's what kind of hooked me into the story or the problem-solving nature of geology, the observational problem solving.
• 24:38
  SPEAKER_01: So this is a really transformative field trip for me.
• 24:41
  SPEAKER_01: But the question is why don't you go to copper country?
• 24:45
  SPEAKER_01: Why don't you go a little bit further and get into these beautiful copper minerals and the really interesting geology there?
• 24:50
  SPEAKER_01: Is it just a time thing?
• 24:50
  SPEAKER_00: It's like too far to drive further, or what's the No, so I used to and I did when I took your class there, but you weren't able to go because of football season.
• 24:59
  SPEAKER_00: So I've done that many, many, many times actually.
• 25:02
  SPEAKER_00: So in the fall, we would go up to we'd go all the way up to Keweenaw Peninsula, and that was a five-day trip.
• 25:10
  SPEAKER_00: But it's very logistically very difficult to do because in the fall you have so many athletics to work around and so on.
• 25:17
  SPEAKER_00: Schedules are just busy, you know, and they've it that's only gotten worse as time has gone on.
• 25:22
  SPEAKER_00: But yeah, used to do that, haven't done that one in a while, probably been maybe 10 years since I've done that trip.
• 25:28
  SPEAKER_00: The other thing, too, Jesse, is because now I teach astronomy, just the way my schedule is, I don't start teaching my geology class until November.
• 25:38
  SPEAKER_00: Does that make sense?
• 25:39
  SPEAKER_01: It's a little bit late.
• 25:40
  SPEAKER_01: Yeah, yeah, it's a little bit late.
• 25:41
  SPEAKER_01: And in the spring, you you end up getting pretty far north.
• 25:43
  SPEAKER_01: Yeah.
• 25:43
  SPEAKER_01: Yeah, and in the spring, you kind of it's the weather's a little bit sticky at the time you can go there.
• 25:48
  SPEAKER_00: Yeah, I'm not taking I'm not gonna take my geology class to the upper upper peninsula in the middle of November.
• 25:54
  SPEAKER_00: That's not a good idea.
• 25:56
  SPEAKER_01: A bunch of suffering students.
• 25:58
  SPEAKER_01: I mean, it's a beautiful place and a good place to lead off on the copper minerals here because native copper is like what this area is famous for.
• 26:05
  SPEAKER_01: Huge amounts of copper were mined historically, and there's some some talk of reopening some of these mines now with the need of copper, as we talked about before.
• 26:14
  SPEAKER_01: But native copper, it's just pure copper.
• 26:16
  SPEAKER_01: It's beautiful.
• 26:17
  SPEAKER_01: My undergrad research project was on some of the copper mineralizing fluids up in the upper peninsula of Michigan, and it is just a beautiful mineral.
• 26:25
  SPEAKER_01: It's technically a mineral, and so that's the simplest one.
• 26:28
  SPEAKER_00: That's right.
• 26:28
  SPEAKER_00: But in the tailine piles, that's where we find these associated minerals that are also really, really kind of cool.
• 26:36
  SPEAKER_00: And we're talking about minerals like chalcopyrite and bornite and chalcosite, all three of these I use extensively in my geology class for identification purposes.
• 26:47
  SPEAKER_00: I think because I've been able to collect a lot of them, and also they're just they're stunningly beautiful.
• 26:53
  SPEAKER_00: And and with metals, and when you're doing mineral identification, it's such a cool thing to throw these things at beginning students because they have different physical properties than normal minerals, right?
• 27:04
  SPEAKER_00: Like they leave a distinctive streak and and their hardnesses are you know on the low end of the scale typically.
• 27:11
  SPEAKER_00: And so they're just kind of neat for them to be able to like do these physical tests on them and get definitive results.
• 27:18
  SPEAKER_01: Exactly.
• 27:19
  SPEAKER_01: And I think this kind of speaks to the complexity of the chemistry of copper or the geochemistry of copper, because copper can be a major constituent element for a whole bunch of different minerals, a whole bunch of different mineral categories, from silicates to carbonates to sulfides to native copper.
• 27:35
  SPEAKER_01: And so some of the sulfides like calcopyrite and boronite are copper iron sulfides.
• 27:40
  SPEAKER_01: It's just a different proportion of copper and iron and sulfur in there.
• 27:43
  SPEAKER_01: Chalcocite and covalite are different copper sulfides, so just pure C US, copper sulfur, whereas azurite and malachite are different proportions of copper and a whole bunch of carbonate and water in there.
• 27:55
  SPEAKER_01: Like you can get really crazily different minerals.
• 27:58
  SPEAKER_01: Crysocola is another one, like it's a silicate.
• 28:00
  SPEAKER_01: Copper's a major constituent phase of that.
• 28:02
  SPEAKER_00: Crysocola is one of my favorites, and here's the reason it has a really weird physical property.
• 28:08
  SPEAKER_00: It sticks to your tongue.
• 28:10
  SPEAKER_00: It's a little bit like putting your tongue on a frozen light pole.
• 28:14
  SPEAKER_00: The only thing is that it won't rip the flesh off your tongue when you you know when you pull the crystal cola away.
• 28:20
  SPEAKER_00: But it's just kind of a cool.
• 28:21
  SPEAKER_00: I use this one in my lab also because I have a ton of it, and it's kind of cool when I see these students like sticking it onto their tongues, and it's tacky and it it pulls it's like uh another another uh mineral to lick in the in the geology class.
• 28:34
  SPEAKER_01: That and halite.
• 28:35
  SPEAKER_00: That's right.
• 28:36
  SPEAKER_00: Oh yeah, oh yeah.
• 28:37
  SPEAKER_00: They lick halite all the time.
• 28:38
  SPEAKER_00: Anyway, malachite and azurite, these are beautiful minerals.
• 28:43
  SPEAKER_00: Azurite is.
• 28:44
  SPEAKER_01: Let me interrupt real quick, Chris.
• 28:45
  SPEAKER_01: I mean, if you're a mineral collecting fan, you know these things.
• 28:49
  SPEAKER_01: If you're not, Google it.
• 28:50
  SPEAKER_01: You will be very soon a mineral collecting fan because they're just stunningly beautiful minerals.
• 28:55
  SPEAKER_00: Sorry, I mean the colors.
• 28:57
  SPEAKER_00: No, that's great.
• 28:58
  SPEAKER_00: The colors are amazing.
• 28:59
  SPEAKER_00: Azurite is named this because of its Azure, deep, deep blue color.
• 29:04
  SPEAKER_00: I got a little defensive when you said is azurite your favorite mineral.
• 29:07
  SPEAKER_00: The reason it's why it's not, I think, is because it's at least in my experience, it's less common than malachite, so I have more malachite.
• 29:16
  SPEAKER_00: I just malachite is this really, really beautiful green color, and green is my favorite color, by the way.
• 29:23
  SPEAKER_00: So malachite's my favorite mineral.
• 29:25
  SPEAKER_00: It's just that's awesome.
• 29:26
  SPEAKER_01: I mean, that you it's such a beautiful one.
• 29:28
  SPEAKER_01: So the point here is that there's a lot of different minerals of different categories that have copper in them that are important copper-bearing minerals, and that speaks to the complexity of copper geochemistry.
• 29:38
  SPEAKER_01: And so I think, Chris, maybe let's move into the types of copper deposits, which you know, we're not giving away the story here.
• 29:46
  SPEAKER_01: It's complicated.
• 29:47
  SPEAKER_01: There's a bunch of different types of deposits that concentrate copper.
• 29:50
  SPEAKER_01: See above all these different minerals that contain copper.
• 29:53
  SPEAKER_01: So of course they can form in different environments.
• 29:55
  SPEAKER_01: But let's go through and sort of summarize the big ones here.
• 29:58
  SPEAKER_00: Yeah, we're only going to hit the big ones.
• 30:00
  SPEAKER_01: Let's start with the big dog, the best one, the coolest one, native copper.
• 30:04
  SPEAKER_01: I mean, I don't know, you you've run this trip up to the QAnon Peninsula.
• 30:07
  SPEAKER_01: What do you got on native copper?
• 30:09
  SPEAKER_01: That's like ground zero for native copper formation.
• 30:12
  SPEAKER_00: So when we talk about native copper, we just mean that it hasn't combined with anything.
• 30:16
  SPEAKER_00: So this is pure copper.
• 30:18
  SPEAKER_00: This almost always occurs in pure copper veins.
• 30:22
  SPEAKER_00: So I've been in many mines in the upper peninsula and with permission, and some sometimes you have to pay to get in, and sometimes you don't.
• 30:30
  SPEAKER_00: Okay, and I've I've done actually both of them.
• 30:33
  SPEAKER_00: But it's really kind of an interesting thing.
• 30:35
  SPEAKER_00: When you're going into a copper vein mine, but the students don't know a ton about it, and you're like, okay, let's take 10 minutes and look around in this network of tunnels and so on in this in this mine, because this is not an open pit mine usually, at least not my experience.
• 30:51
  SPEAKER_00: Most of them have no idea what to do and where to look.
• 30:54
  SPEAKER_00: And really what you're doing is you're looking for for cracks in the rock, and you shine a flashlight on either side of that crack, and and you can see then literally it looks like a sheet of paper, a thick sheet of paper, this vein that's squirted up into the crack in the rock.
• 31:10
  SPEAKER_00: And so that's kind of what this looks like.
• 31:12
  SPEAKER_00: And then you got to do some chiseling to kind of exploit the vein and peel the copper off the wall.
• 31:17
  SPEAKER_00: But it's awesome.
• 31:19
  SPEAKER_00: I've got tons of this stuff.
• 31:20
  SPEAKER_00: Well, not tons.
• 31:21
  SPEAKER_00: I mean, I I have I have some impressive sheets of copper that are that I use at school quite a bit.
• 31:25
  SPEAKER_01: I mean, it's super beautiful stuff.
• 31:27
  SPEAKER_01: Uh, it's just a really it's an amazing element, uh, an amazing deposit type, because it's just it's just right there, pure copper.
• 31:34
  SPEAKER_01: You just haul it off a big chunk of pure copper.
• 31:37
  SPEAKER_01: The biggest chunk, actually, of elemental pure copper of native copper, weighed 420 tons, and this was discovered in 1857.
• 31:46
  SPEAKER_01: So that's a very economical copper deposit right there.
• 31:50
  SPEAKER_01: You just pull it off the wall and boom, there it is.
• 31:53
  SPEAKER_01: You can just string that out into wire pretty easily.
• 31:56
  SPEAKER_00: Amazing.
• 31:57
  SPEAKER_00: You know how they used to get this out and separate the rock in these vein deposits, separate the rock from the metal.
• 32:06
  SPEAKER_00: Was they would take the rock, the ore that had the copper in it, and they put it on this flat slab, and they had this gigantic piston, this other really hard rock that was like a piston that was it went up and down and crushed the rock, and it was they used horses and mules to turn a wheel that lifted and smashed the rock.
• 32:27
  SPEAKER_00: And so there are places up at the UP where you can see this, what they call stamp sand, which is where they crushed the rock and flattened the copper out, you know, and the stamp sand is all of the pulverized material that was uh kind of separated from the copper, anyway.
• 32:43
  SPEAKER_01: Just that's a really I didn't I didn't know that.
• 32:45
  SPEAKER_01: That's that's super cool.
• 32:46
  SPEAKER_01: Just real quick, the the way that, at least in this area of the QL peninsula up in the upper peninsula of Michigan, the reason that copper's concentrated there is that this is what's called the mid-continent rift event.
• 32:57
  SPEAKER_01: And this is where basically a failed ocean basin.
• 32:59
  SPEAKER_01: So the continent tried to break apart and it failed.
• 33:02
  SPEAKER_01: And during that breakup, we've talked about mid-ocean ridges before, and we've talked about big basaltic eruptions before, kilometers of basalt.
• 33:11
  SPEAKER_00: Pillow basalts and so on.
• 33:12
  SPEAKER_01: In pillow basalts, we can see them up there behind the menards, what used to be that they've destroyed it now.
• 33:17
  SPEAKER_01: But these basalts were erupted and like two kilometers of basalt, a lot of basalt was erupted.
• 33:23
  SPEAKER_01: And the way that this stuff gets concentrated is basically it's just burial metamorphism, two kilometers of basalt.
• 33:29
  SPEAKER_01: The bottom basalt layer is being metamorphosed by the heat and pressure of burial.
• 33:35
  SPEAKER_01: And some people have estimated that all of the copper that's all the native copper that's up in there, it could have very easily been sourced from just the basalt.
• 33:42
  SPEAKER_01: So just this burial metamorphism, fluids sort of percolating up through this two-kilometer thick package of basalt could just extract the copper from the basalt and then concentrate it up near the surface.
• 33:53
  SPEAKER_01: So that's right.
• 33:54
  SPEAKER_01: That's one environment.
• 33:55
  SPEAKER_00: Can I take a take can I take a swing at this one a second?
• 33:57
  SPEAKER_00: It's it's like if you take super hot water and then make the water not only hot but salty, and it percolates through vast volumes of rock.
• 34:07
  SPEAKER_00: All rock has these native elements in it.
• 34:10
  SPEAKER_00: So hot, salty water.
• 34:12
  SPEAKER_00: Copper is it's easily dissolved in this.
• 34:15
  SPEAKER_00: And so as water sweeps through this vast volume of rock that's highly busted up and it's super hot, the conditions are just right.
• 34:22
  SPEAKER_00: And like you said, it rises up and then conditions change, which causes it to concentrate in the upper layers there, and then it kind of gets sealed off, and there's a lot of other things that are going on.
• 34:33
  SPEAKER_00: But if you want to make it really simple, mid-ocean ridges in these rift systems can provide a mechanism for low concentrations of copper to accumulate due to those geologic settings and and kind of the setting that you just described.
• 34:51
  SPEAKER_01: That's exactly right.
• 34:52
  SPEAKER_01: Um, that's a great, great description and a nice simplification there, Christopher.
• 34:56
  SPEAKER_01: That was well well done.
• 34:57
  SPEAKER_01: Well done.
• 34:58
  SPEAKER_01: Keeping us out of the weeds as usual.
• 35:00
  SPEAKER_00: I'm trying.
• 35:01
  SPEAKER_00: Well, Jesse, let's go to number two.
• 35:03
  SPEAKER_00: Okay, let's talk about the copper porphyry.
• 35:06
  SPEAKER_00: And I'm gonna let you kind of lead this out here.
• 35:09
  SPEAKER_00: But remember way back when, I don't know, we've done episodes on this before, what a porphyritic rock is.
• 35:16
  SPEAKER_00: A porphyritic rock is a rock that has two rates of cooling.
• 35:20
  SPEAKER_00: When igneous rocks cool slowly, the crystals tend to get very large, and then they then it cools fast when volcanism happens and it it sweeps these early formed, slow, you know, forming crystals with it, and it entombs them in this really, really fine-grained matrix.
• 35:36
  SPEAKER_00: And so you get this porphyritic rock, which is a rock that has two very distinct grain sizes in it from two very distinct rates of cooling.
• 35:44
  SPEAKER_00: So that's the kind of rock that's hosting this.
• 35:48
  SPEAKER_00: Where does this kind of happen then, Jesse?
• 35:50
  SPEAKER_01: Yeah, so porphyry deposits, copper porphyry deposits, are named for the rock type because you have this big giant copper deposit sitting somewhere, and right in the center there'll be a porphyritic rock, usually like a porphyritic granite that's sort of right in the center.
• 36:03
  SPEAKER_01: And as you said, it'll have this these big grains and smaller grains, or normal granity grains and then big, big, big grains, like uh megachrystic grains.
• 36:11
  SPEAKER_01: And so think of if anybody's been to Yosemite National Park, like you've been there, Chris, these big feldspars, these big potassium feldspars kind of in the center, disseminated in the granite.
• 36:21
  SPEAKER_01: That's what we're talking about.
• 36:22
  SPEAKER_01: And so the way to think about this is a big granite body intrudes.
• 36:25
  SPEAKER_01: There's a lot of heat and magmatic fluids that are fluxing through the rock around it.
• 36:30
  SPEAKER_01: And basically, short summary is that that concentrates copper in the rocks above it.
• 36:35
  SPEAKER_01: And so the magma, there's this big magma system going way deep down beneath the magma body.
• 36:41
  SPEAKER_01: So we've got a little magma chamber up at the surface, what ends up being the porphyry, but it there's a ton of stuff beneath there that has copper in it that's kind of pushing fluids up through this reservoir, and then the copper will get deposited kind of on the halo, in the halo around the granite, around the porphyry rock.
• 37:00
  SPEAKER_01: So that's kind of a way to think about this.
• 37:02
  SPEAKER_00: Okay, so it's really a metamorphic rock surrounding a porphyry, right?
• 37:08
  SPEAKER_01: Yeah, that's a great description, Chris.
• 37:10
  SPEAKER_01: It's just this like hyper-mineralized sort of reaction rim around a magma body.
• 37:16
  SPEAKER_01: And it's often right above the magma body.
• 37:18
  SPEAKER_01: So this is the kind of tricky part about copper porphyry deposits, is they often form sort of just above the magma chamber.
• 37:25
  SPEAKER_01: So if you erode this to any great detail, you're gonna lose it.
• 37:28
  SPEAKER_01: So, like the Sierra Nevadas, Yosemite National Park, there was probably a porphyry deposit above those rocks, like kilometers above those rocks.
• 37:36
  SPEAKER_01: Those have been eroded down to like nine kilometers, six to nine kilometers depth now.
• 37:40
  SPEAKER_01: So the copper porphyry deposit has been eroded away because it sat just above it, kind of in between the magma chamber and the volcano.
• 37:47
  SPEAKER_01: You can think of it that way.
• 37:48
  SPEAKER_01: It's kind of in the system between the magma chamber and the volcano, kind of in that plumbing system where groundwater is interacting with magmatic water and magmatic gases, and it's this really complicated environment.
• 37:59
  SPEAKER_00: So if you erode that away, then it's probably then going to be concentrated in a sedimentary rock than right as a placer.
• 38:08
  SPEAKER_01: I know that's typical with gold.
• 38:10
  SPEAKER_01: It certainly can be, but copper, um, its geochemistry is much more complicated than gold, so it's usually like reabsorbed into water and carried off, and it's sort of disseminated again when that happens sometimes.
• 38:21
  SPEAKER_01: Where these things form, we're talking about these types of magma systems, these kind of subduction zone type magma systems.
• 38:28
  SPEAKER_01: So the biggest copper mining places in the world are where former or modern subduction zone systems are occurring.
• 38:34
  SPEAKER_01: So think Chile, Argentina, the west coast of the United States, actually Arizona, Utah, up into British Columbia, up into Canada, huge copper mines in there.
• 38:45
  SPEAKER_00: Yeah, interesting that you say this because uh I find that a lot of the porphyritic andesite in the absericas in Yellowstone and outside of Yellowstone have tons of disseminated copper in it.
• 38:58
  SPEAKER_00: And when we say disseminated, we're talking about like specks of copper within the porphyrytic igneous rock itself.
• 39:05
  SPEAKER_00: There's a actually a fair amount.
• 39:07
  SPEAKER_00: I mean, you don't have to look very hard to say, wait a minute, that looks like there's malachite there, you know.
• 39:12
  SPEAKER_00: You can see that, and it and and you can see some of the actual like native copper in it, too.
• 39:17
  SPEAKER_00: It's really kind of cool, but and that makes sense because it that's a subduction zone kind of thing.
• 39:23
  SPEAKER_01: So the copper is kind of coming.
• 39:25
  SPEAKER_01: We can source the copper kind of from the mantle.
• 39:27
  SPEAKER_01: That's the ultimate source of the copper, and it's kind of pumping through this magma system and then being concentrated right on the upper, very, very top of this entire sort of system that traverses the crust.
• 39:38
  SPEAKER_01: And Bingham Canyon Mine in Utah is this is an interesting statistic.
• 39:42
  SPEAKER_01: It's the largest man-made excavation ever.
• 39:45
  SPEAKER_01: And it has been producing copper since 1906.
• 39:48
  SPEAKER_01: And Chris, 17 million tons of copper have been produced from this mine.
• 39:54
  SPEAKER_01: It is ginormous.
• 39:56
  SPEAKER_01: I mean, just a huge, huge, huge deposit.
• 40:01
  SPEAKER_01: If we get that like you erode the volcano away just enough so that you're at that perfect level, you're not into the magma chamber, the former magma chamber, but you're kind of in that Goldilocks environment.
• 40:11
  SPEAKER_01: You can just get massive concentrations of copper.
• 40:13
  SPEAKER_00: That's amazing.
• 40:14
  SPEAKER_00: However, when you look at world consumption and you know how much copper is mined annually, 17 million tons, it doesn't even cover the amount that is mined annually throughout the world.
• 40:28
  SPEAKER_00: A few years ago, we were at just over 20 million tons.
• 40:32
  SPEAKER_00: Two years ago, we were at 21 million tons, and it's projected to just increase a lot more.
• 40:37
  SPEAKER_00: And obviously, we talked about that at the top of the show.
• 40:40
  SPEAKER_00: So crazy numbers, yet the world consumption is even crazier, in my opinion.
• 40:45
  SPEAKER_01: Yeah, I agree completely.
• 40:47
  SPEAKER_01: These deposits, finding big deposits like that are kind of the goal or the target, right?
• 40:52
  SPEAKER_01: Or finding a whole bunch of different ones.
• 40:54
  SPEAKER_01: So let's move on to just the last deposit type, which is kind of a major one.
• 40:58
  SPEAKER_01: You don't get the huge deposits of these.
• 41:00
  SPEAKER_01: They're not like the super ginormous copper deposits, but they are are still important, is volcanic massive sulfide deposits.
• 41:07
  SPEAKER_01: And the way to think about this, Chris, I think there's there's a great video out there, many videos, of took these submersibles, we, the royal we took submersibles down to the sea floor and went to mid-ocean ridges and saw these black smoker vents, these things that are just pumping out these super hot, super aggressive fluids from the oceanic crust.
• 41:28
  SPEAKER_01: That's kind of what's happening here.
• 41:30
  SPEAKER_01: These really put that they're pumping out copper and lead and sulfur and iron in those fluids.
• 41:36
  SPEAKER_01: These black smokers are just pumping that stuff out.
• 41:39
  SPEAKER_01: And so I don't know, that that's kind of one way to think about volcanic massive sulfide deposits is they're sulfide hosted, they're being pumped out of at the base of an ocean, at the seafloor, and usually these are forming near mid-ocean ridge settings or near kind of volcanic provinces that are underneath of the ocean floor or at the at the seabed level.
• 41:59
  SPEAKER_00: There is a theme here.
• 42:01
  SPEAKER_00: All three of the mechanisms that we've talked about involve volcanism on one level or another.
• 42:07
  SPEAKER_00: Uh that's true, you know, at least in terms of we're only talking about the the big ways in which copper forms.
• 42:14
  SPEAKER_00: It does get very complicated.
• 42:16
  SPEAKER_00: And one thing that I do want to mention about this, you know, volcanic massive sulfide or VMS deposits is that it's really the geochemistry is absolutely amazing.
• 42:27
  SPEAKER_00: And if you're interested, we'll put a link in the show notes to an article that talks a little bit about this.
• 42:33
  SPEAKER_00: It's it's really uh it's a cool thing because it it talks about how these sulfide minerals start off as one mineral and then how they change as they're put in kind of these different geoscience settings.
• 42:46
  SPEAKER_00: And it's just I think it's amazing, but it uh it goes beyond the scope of the show.
• 42:50
  SPEAKER_00: Joyce is lost at this point, and you know, so hey, give Joyce a little credit.
• 42:55
  SPEAKER_01: I think she's followed along.
• 42:56
  SPEAKER_01: We'll we'll get her response.
• 42:57
  SPEAKER_01: Joyce, send us an email.
• 42:58
  SPEAKER_01: Chris won't read it, but I promise I will.
• 43:00
  SPEAKER_01: And uh let us know, let us know how this episode landed with you, will you?
• 43:04
  SPEAKER_00: Yeah, you're you're probably gonna get two emails.
• 43:07
  SPEAKER_00: One is from Joyce, so you should she might send you more than that.
• 43:10
  SPEAKER_00: And then hopefully, Dave.
• 43:12
  SPEAKER_00: Hopefully, Dave is gonna send you an email to um, you know, we'll be able to do it.
• 43:15
  SPEAKER_01: He'll listen to about minute 10 where we start talking about biology and then tune out for the rest of it.
• 43:20
  SPEAKER_01: But uh That's right.
• 43:21
  SPEAKER_00: That's right.
• 43:21
  SPEAKER_00: He'll be lost in thought.
• 43:23
  SPEAKER_01: There's a lot to unpack even further about copper and about these really complicated elements and and geochemistry of these things.
• 43:29
  SPEAKER_01: But I think we did a bit of justice to it, and it's a really timely thing because copper, even though it's used in everybody's house and in everybody's car, it's super important for the future sort of green energy transition that we're currently undergoing or starting to undergo right now.
• 43:44
  SPEAKER_01: So, yeah, something to think about when you're walking around out there in the world.
• 43:46
  SPEAKER_01: It's not going away.
• 43:47
  SPEAKER_01: It's here to stay.
• 43:48
  SPEAKER_01: It's not going away.
• 43:49
  SPEAKER_01: That's right.
• 43:49
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• 43:55
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• 43:58
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• 43:59
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• 44:04
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• 44:06
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• 44:08
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• 44:13
  SPEAKER_01: Go to the first link in our show notes.
• 44:15
  SPEAKER_01: You can learn with uh audio discussions and images what we teach Chris, you and I in our uh introductory geoscience classes.
• 44:21
  SPEAKER_00: Gearing up for it right now.
• 44:23
  SPEAKER_01: There we go.
• 44:24
  SPEAKER_01: Cheers.
• 44:25
  SPEAKER_01: Peace.