# What metal are these lab crucibles made of? **URL:** \ **Category:** Factual Questions\ **Created:** [June 8, 2012, 11:08am UTC](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484 "2012-06-08T11:08:10Z")\ **Posts on this page:** 14\ **Page:** 2
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [June 9, 2012, 3:19am UTC](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484/21 "2012-06-09T03:19:47Z")
> [@pravnik](#): > > Zirconium has a melting point of 3371 °F, while tungsten’s is 6192 °F. Just set your kitchen oven for around 4000 degrees, and if it melts, it was zirconium. Use the good oven mits. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [June 9, 2012, 1:46pm UTC](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484/22 "2012-06-09T13:46:59Z")
Thanks all. I know I could use density, but it would be hard to get a good estimate of their volume, as they occupy a large physical volume in a container yet displace a small volume of liquid because they are hollow. This means I’d lower them into a cylinder of water maybe 60 or 70 mm in diameter, and the meniscus would go up by maybe 2 mm, and the uncertainty in estimating that 2 mm translates into uncertainty in volume and density. If I can estimate the 2 mm to within 1 mm, which I doubt, I would have a factor of two uncertainty in the final estimate of density. I could run SEM/EDS more cheaply than I could do that experiment, anyway, considering how long it would take to do a good enough job to compare two meniscus heights with an uncertainty budget smaller than 1 mm. No, I like suggestions like “zirconium” (because I didn’t think of it) and “lead is soft, wouldn’t ring, and wouldn’t work for high temps” (which was obvious to me from the start but is the kind of logic and nifty facts I am looking for). I wonder if platinum gets a dark gray color with hints of brown and purple - can anybody tell me this? I imagined it might stay silvery bright, but have zero experience with platinum at high temperature. I ask the same question about zirconium. I have a chunk of zirconium - yes, the elemental metal, probably 4N - in my bedroom. But my bedroom tops out at around 26 C. I do have just a little experience with tantalum at high temp, and I can imagine it getting this look but am not sure. Tungsten is an interesting suggestion. I have two elemental tungsten cylinders in my bedroom, too, and they have been shiny for a couple years now, but I also have a roll of tungsten wire, and it maintains a gritty dusty surface, which I think I heard was tungsten oxide, and I also used a slab of tungsten (maybe 15 kg or so) at work for a while, which tended to get dusty, so I am a little confused as to its surface finish tendency when left out over time. There’s also the question of whether the tungsten is a sintered powder, or perhaps formed with a binder metal as a composite (not an alloy). I have worked with stellite, which I understand is the latter. These crucibles look to me like they are deep drawn, like an aluminum briefcase shell, and somehow it’s hard to imagine tungsten cooperating with a process like deep drawing. As to tungsten carbide, well, there’s no way somebody’s going to manufacture articles by deforming sheet tungsten carbide, right? You’d have better luck tying knots in concrete posts. Finally, as to graphite, it depends on the form I think. Graphite usually looks less silvery than these do (which isn’t much), except pyrolytic graphite, which looks much glossier and glassier. I think graphite would feel several times less dense, too. I don’t know how it would be fabricated into this form. I would guess as compressed sintered powder, but in that case the crucible would have more of a thick shape with conical exterior, I think. But I just don’t know much about it. Cool guesses - keep 'em coming! ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [June 9, 2012, 1:58pm UTC](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484/23 "2012-06-09T13:58:49Z")
They look more like the molybdenum crucibles here: [http://www.worldtungstens.com/en/Molybdenum/Molybdenum-Crucibles.html](http://www.worldtungstens.com/en/Molybdenum/Molybdenum-Crucibles.html) than any of the platinum, zirconium, tantalum, tungsten, or graphite crucibles I found online. They have a cylindrical shape, and the sides are parallel, with no visible cone. The wall thickness looks like 2 mm and appears constant. The bottom is flat, inside and out. There is a significant radius to the bottom inside corner, maybe 4 mm or so on the inside. There are also some lids that certainly look stamped, that is, a central region and a perimeter region that are each planar and parallel but the central region is displaced by maybe 3 mm axially. ---
**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\ **Post date:** [June 9, 2012, 2:27pm UTC](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484/24 "2012-06-09T14:27:43Z")
Is there a materials engineering department there with an energy-dispersive X-ray (EDX) spectroscope handy? They could tell you in a few seconds what you have there. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [June 9, 2012, 4:05pm UTC](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484/25 "2012-06-09T16:05:12Z")
> [@ElvisL1ves](#): > > Is there a materials engineering department there with an energy-dispersive X-ray (EDX) spectroscope handy? They could tell you in a few seconds what you have there. Yes, or something like that. That’s what I thought was called SEM/EDS meaning “…electron dispersive spectroscopy” or something like that. I can only remember a few hundred acronyms and that one is too far down the list to get included any more. But, yeah, we have things for that. Filling out all the forms and tracking down account numbers for it wasn’t as appealing as learning something about crucibles here, though. I should state that I don’t absolutely have to figure this out, and if I did have to, I have a (tedious) way. This was for fun, learning, and fighting ignorance. I still bet there are people who would take one look at these and know what they are. Of course, that could be my over optimism! ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [June 9, 2012, 4:25pm UTC](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484/26 "2012-06-09T16:25:10Z")
As per the other thread on mystery metal. To get the density you don’t need to measure the volume. If you have a beam balance, weigh a crucible hanging on a thread in air, and then weigh it hanging in a glass of water. The difference in weights times density of water is the volume. Since density is usefully given in units of density of water you never even have to know the density of water. Density = weight in air/ (weight in air - weight in water) ---
**Author:** ![VOW](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/vow/32/3043_2.png) [@VOW](https://boards.straightdope.com/u/VOW)\ **Post date:** [June 9, 2012, 7:21pm UTC](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484/27 "2012-06-09T19:21:19Z")
> [@Napier](#): > > Thanks all. > > I know I could use density, but it would be hard to get a good estimate of their volume, as they occupy a large physical volume in a container yet displace a small volume of liquid because they are hollow. This means I’d lower them into a cylinder of water maybe 60 or 70 mm in diameter, and the meniscus would go up by maybe 2 mm, and the uncertainty in estimating that 2 mm translates into uncertainty in volume and density. If I can estimate the 2 mm to within 1 mm, which I doubt, I would have a factor of two uncertainty in the final estimate of density. > > I could run SEM/EDS more cheaply than I could do that experiment, anyway, considering how long it would take to do a good enough job to compare two meniscus heights with an uncertainty budget smaller than 1 mm. > > No, I like suggestions like “zirconium” (because I didn’t think of it) and “lead is soft, wouldn’t ring, and wouldn’t work for high temps” (which was obvious to me from the start but is the kind of logic and nifty facts I am looking for). > > I wonder if platinum gets a dark gray color with hints of brown and purple - can anybody tell me this? I imagined it might stay silvery bright, but have zero experience with platinum at high temperature. > > I ask the same question about zirconium. I have a chunk of zirconium - yes, the elemental metal, probably 4N - in my bedroom. But my bedroom tops out at around 26 C. > > I do have just a little experience with tantalum at high temp, and I can imagine it getting this look but am not sure. > > Tungsten is an interesting suggestion. I have two elemental tungsten cylinders in my bedroom, too, and they have been shiny for a couple years now, but I also have a roll of tungsten wire, and it maintains a gritty dusty surface, which I think I heard was tungsten oxide, and I also used a slab of tungsten (maybe 15 kg or so) at work for a while, which tended to get dusty, so I am a little confused as to its surface finish tendency when left out over time. There’s also the question of whether the tungsten is a sintered powder, or perhaps formed with a binder metal as a composite (not an alloy). I have worked with stellite, which I understand is the latter. These crucibles look to me like they are deep drawn, like an aluminum briefcase shell, and somehow it’s hard to imagine tungsten cooperating with a process like deep drawing. As to tungsten carbide, well, there’s no way somebody’s going to manufacture articles by deforming sheet tungsten carbide, right? You’d have better luck tying knots in concrete posts. > > Finally, as to graphite, it depends on the form I think. Graphite usually looks less silvery than these do (which isn’t much), except pyrolytic graphite, which looks much glossier and glassier. I think graphite would feel several times less dense, too. I don’t know how it would be fabricated into this form. I would guess as compressed sintered powder, but in that case the crucible would have more of a thick shape with conical exterior, I think. But I just don’t know much about it. > > Cool guesses - keep 'em coming! Dude! You got all that crap in your BEDROOM? You been kyping stuff in the labs for years? ~VOW ---
**Author:** ![Shosy](https://avatars.discourse-cdn.com/v4/letter/s/919ad9/32.png) [@Shosy](https://boards.straightdope.com/u/Shosy)\ **Post date:** [June 9, 2012, 7:46pm UTC](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484/28 "2012-06-09T19:46:59Z")
I still dont understand exactly what these crucibles were for (and crucible of course means something different to a chemist and a metal worker). I’m familiar with 2 common types of “crucible” Lead to deal with highly acidic compounds, like preparing hydroflouric acid to etch glass, and graphite to melt a small steel sample. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [June 9, 2012, 8:47pm UTC](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484/29 "2012-06-09T20:47:31Z")
I’ve never heard of the term ‘crucible’ applying to something not intended to withstand fierce heating - and a Google on “lead crucible” only seems to return: Crucibles intended for melting lead Crucibles made of graphite (AKA ‘black lead’) Could you provide a link? ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [June 9, 2012, 11:37pm UTC](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484/30 "2012-06-09T23:37:36Z")
> [@VOW](#): > > Dude! > > You got all that crap in your BEDROOM? You been kyping stuff in the labs for years? > ~VOW You’ve never read/heard about crucible sex? ---
**Author:** ![asterion](https://avatars.discourse-cdn.com/v4/letter/a/4da419/32.png) [@asterion](https://boards.straightdope.com/u/asterion)\ **Post date:** [June 10, 2012, 1:09am UTC](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484/31 "2012-06-10T01:09:40Z")
> [@Napier](#): > > Yes, or something like that. That’s what I thought was called SEM/EDS meaning “…electron dispersive spectroscopy” or something like that. I can only remember a few hundred acronyms and that one is too far down the list to get included any more. But, yeah, we have things for that. Filling out all the forms and tracking down account numbers for it wasn’t as appealing as learning something about crucibles here, though. > > I should state that I don’t absolutely have to figure this out, and if I did have to, I have a (tedious) way. This was for fun, learning, and fighting ignorance. I still bet there are people who would take one look at these and know what they are. Of course, that could be my over optimism! I think a LIBS is just about what you need. Tiny amount of damage to the exterior wall, quick and easy to use, and who doesn’t love laser ablation? ---
**Author:** ![Saltire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saltire/32/553_2.png) [@Saltire](https://boards.straightdope.com/u/Saltire)\ **Post date:** [June 10, 2012, 2:22am UTC](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484/32 "2012-06-10T02:22:53Z")
All you have to do is put it next to a bit of plutonium for a few hours, and then measure the radioactivity coming off the crucible a few times. The frequency of the photons and the half-lives you measure, along with a little time with the Rubber Handbook, will tell you what element(s) you’ve got. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [June 10, 2012, 6:26pm UTC](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484/33 "2012-06-10T18:26:10Z")
> [@VOW](#): > > Dude! > > You got all that crap in your BEDROOM? You been kyping stuff in the labs for years? > ~VOW In the bedroom I just have… well… unusual tastes. BTW I think you are only the second person to have called me “Dude”. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [June 10, 2012, 6:28pm UTC](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484/34 "2012-06-10T18:28:10Z")
> [@Saltire](#): > > All you have to do is put it next to a bit of plutonium for a few hours, and then measure the radioactivity coming off the crucible a few times. The frequency of the photons and the half-lives you measure, along with a little time with the Rubber Handbook, will tell you what element(s) you’ve got. There, see? See?? I knew if I posted here, somebody would come along and make it a snap! [Previous page](https://boards.straightdope.com/t/what-metal-are-these-lab-crucibles-made-of/624484.md?page=1)