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Author: Subject: Mystery Metal: ~21.25g/cm3
LanthanumK
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[*] posted on 23-6-2012 at 11:54


Use scratch tests with various materials (glass, knife, quartz, etc.) to determine Mohs' hardness. Tungsten has 7.5 hardness, platinum 4, and rhenium 7. If it can be scratched by a knife with difficulty, it is probably platinum.



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phlogiston
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[*] posted on 23-6-2012 at 13:13


rhenium dissolves in nitric acid, tungsten and platinum do not.

tungsten dissolves in warm, 30% hydrogen peroxide to give a yellow solution, platinum does not.

If the rod's diameter is uniform over its length, the volume measurement should be sufficiently accurate, and probably more so than typically achieved by immersion.

Quote:
None directly. It was not a rant, merely a little piece of satire based upon the actual likelihood of it actually being true, which is vanishingly small. Have you ever seen a piece of machined pure tungsten? What use would it be?


Unlikely events happen. It is not as if we hear this story on a regular basis.

Although you may not be able to think of any, these things exist and are used. Keep in mind he worked in a pretty unusual place.
Machined tungsten items are easy to find online:


Quote:
People do not have about $9000 worth of shiny Pt rod or large billets of W in their basements.


Apparantly, some people do. You should check out some of the wonderful items some element collectors have.




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Fleaker
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[*] posted on 23-6-2012 at 17:01


If you want, you can send it to me. I will use XRF analysis on it and tell you what it is. It's either platinum, rhenium, or iridium (it isn't osmium, I can tell that right away--plus that's so difficult to cast or sinter).

Looks like an iridium rod to me.

Quote:

People do not have about $9000 worth of shiny Pt rod or large billets of W in their basements.


I know people who have way more expensive quantities of PGMs or other elements in their collection. I have a good friend of mine is a metallurgist who has quite the collection of 5 and 10 kg sputtering targets out of Ta, Hf, Re, Zr, Nb, and W.

Attached is a piece of 9995 platinum so you can see its cast.

IMG_1053.jpg - 17kB

[Edited on 24-6-2012 by Fleaker]




Neither flask nor beaker.


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unionised
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[*] posted on 24-6-2012 at 04:36


Quote: Originally posted by DerAlte  
unionised wrote: Any evidence for that rant?

None directly. It was not a rant, merely a little piece of satire based upon the actual likelihood of it actually being true, which is vanishingly small. Have you ever seen a piece of machined pure tungsten? What use would it be?

Der Alte

Yes, I have.
It was the electrode from a high power flash lamp.
Do you realise that your ignorance doesn't stop other people finding a use for it?
Incidentally, I also have a tin with 5Kg of tungsten sponge in it. It was chucked out as scrap so I git it for free. Not as valuable as a single rod, but quite a nice find.
Also, I rather suspect that they start with lengths of rod to make these.
http://www.google.co.uk/search?q=tungsten+darts&hl=en&am...


[Edited on 24-6-12 by unionised]
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cyanureeves
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[*] posted on 24-6-2012 at 04:51


tungsten carbide is not the same as tungsten is it? ebay mostly has tungsten carbide stuff like rings and drill bits but i would like to own tunsten or separate it from the carbide if possible.
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[*] posted on 24-6-2012 at 05:29


The hardness test is a good starting point. Platinum crucibles are pretty easy to scratch with stainless steel.



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blogfast25
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[*] posted on 24-6-2012 at 05:45


At the end of the day really only XRF will lay this to rest easily and conclusively.



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unionised
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[*] posted on 24-6-2012 at 07:28


For a given definition of "easily" - specifically one that includes having access to an XRF rig.
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[*] posted on 24-6-2012 at 07:58


Quote: Originally posted by unionised  
For a given definition of "easily" - specifically one that includes having access to an XRF rig.


Quite a few jewelers have portable Niton XRFs today. If the suspicion is that Ir or Pt might be involved they would willingly oblige, I think.

My own suspicion is that we won't hear from our original poster again...




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Erbium_Iodine_Carbon
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[*] posted on 24-6-2012 at 16:23


I could scratch the rod with a kitchen knife. I also took some pictures with the measurements. I did weigh it on a scale accurate to 0.01g and got a mass of 185.61g.


IMG_6426.JPG - 138kB IMG_6425.JPG - 111kB IMG_6420.JPG - 114kB IMG_6419.JPG - 139kB IMG_6418.JPG - 111kB IMG_6417.JPG - 109kB

[Edited on 25-6-2012 by Erbium_Iodine_Carbon]
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[*] posted on 25-6-2012 at 00:05


Sorry if this has been asked but have you done a specific gravity test on it yet?




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[*] posted on 25-6-2012 at 02:29


Quote: Originally posted by Erbium_Iodine_Carbon  
I could scratch the rod with a kitchen knife. I also took some pictures with the measurements. I did weigh it on a scale accurate to 0.01g and got a mass of 185.61g.


So whats the density now?
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Erbium_Iodine_Carbon
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[*] posted on 25-6-2012 at 03:55


Density was 21.33g/cm3

V=h*pi*r^2
V=10.65*3.14159...*0.51^2
V=8.70cm3

Density=mass/volume
D=185.65/8.70
D=21.33g/cm3

[Edited on 25-6-2012 by Erbium_Iodine_Carbon]
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blogfast25
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[*] posted on 25-6-2012 at 05:02


On photo 5 the rod seems slightly scratched, which would indicate the metal to be 'softish'. And you're certain that the rod isn't tapered, right?

With the suspicion being indeed in the direction of Pt you should really consult a jeweler, preferably one with a Niton XRF. Or take off a small piece and have it XRFed by Fleaker...




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hyfalcon
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[*] posted on 25-6-2012 at 06:06


Close enough for Platinum allowing for measurement error. Man, I would LOVE to have THAT for a perchlorate electrode!
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[*] posted on 25-6-2012 at 06:36


The 5th pic was indeed meant to show where I scratched the rod. I wouldn't use it as a perchlorate electrode by itself because it's surface area is tiny compared with the actual amount of platinum. I'm toying with the idea of dissolving some in aqua regia and plating it onto some other substrate, of course if it does turn out to be Pt.
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[*] posted on 25-6-2012 at 08:18


Quote: Originally posted by Erbium_Iodine_Carbon  
I'm toying with the idea of dissolving some in aqua regia and plating it onto some other substrate, of course if it does turn out to be Pt.


Sure. Add saturated NH4Cl to the solution (assuming you get one) to get yellow (NH4)2PtCl6. Boy, you are one lucky %^$%&%$&(^ if this turns out to be a majority Pt alloy!




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[*] posted on 25-6-2012 at 08:22


Quote: Originally posted by blogfast25  
Quote: Originally posted by Erbium_Iodine_Carbon  
I'm toying with the idea of dissolving some in aqua regia and plating it onto some other substrate, of course if it does turn out to be Pt.


Sure. Add saturated NH4Cl to the solution (assuming you get one) to get yellow (NH4)2PtCl6. Boy, you are one lucky %^$%&%$&(^ if this turns out to be a majority Pt alloy!
I already said this one in this thread. but test for other PGM could be done.



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[*] posted on 25-6-2012 at 08:36


Neat. It's platinum then, or an alloy thereof.


FYI, don't ever use a mixture of ammonium nitrate and HCl to try and dissolve platinum--it does not work.





Neither flask nor beaker.


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[*] posted on 25-6-2012 at 09:03


Interestingly, 187 grams equals 6.012 troy ounces... pretty close to a round number of troy ounces.

At $1440 / oz $US, IF the bar is Pt, then it has a value of approximately $8,640.

I see no reason for it to NOT be Pt, at least in terms of its shape. A solid bar rules out nothing. Big research firms start with all sorts of shapes to turn out finished products. The bar may be the starting shape of any number of Pt objects/devices. And a huge firm, or a government entity, might conceivably have dozens of these stashed away, years ago. The $$ would be piddling to them, and the temptation to lift one would be huge.

Cool find, it'll be interesting to find out what it is.
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[*] posted on 25-6-2012 at 11:42


Humour me.
Take a long thin bottle of water, deep enough to put the rod in.
Put it on the scales and zero them. Tie a thread round the rod and lower it into the water so it is covered but not touching the bottom.
See what the scales read.

The water will exert an up thrust on the metal equal to the weight of water displaced (i.e. the volume of the rod). Since something has to provide that force, there's a downward force on the scales.
Since the density of water is practically 1 g/ml, the weight registered on the scales is the volume of the bar.

Even if this gives you exactly the same value as the measurements with the calliper gauge it will be useful confirmation (always a good thing in science) and it also lets me explain the easy way to measure the volume of an irregular solid.

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[*] posted on 25-6-2012 at 18:43


Really cool idea unionised. I'll need to take note of this.

Who knows maybe the guy was raised in the great depression and instead of hiding his cash under the mattress due to a mistrust in banks he decided to invest in a superfluous platinum rotor. Another interesting idea to take note of.




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[*] posted on 26-6-2012 at 00:07


Yeah, that's really cool unionised, I didn't know that!
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[*] posted on 28-6-2012 at 06:55


Platinum will carry a magnetic field, albeit more weakly than fe or ni, if you have a rare earth or strong magnet leave it attached overnight and see if it magnetises it slightly by morning. I believe this separates the other Pgm possibilities.



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[*] posted on 29-6-2012 at 10:55


@Panache – AFAIK, Pt is paramagnetic in bulk so your test will not work. However, in alloys it is indeed ferromagnetic in combination, eg, with cobalt. Also, apparently in nanoparticles:
http://www.phantomsnet.net/files/abstracts/TNT2005/TNT05_Fer...
Also see www.platinummetalsreview.com/pdf/pmr-v8-i1-009-011.pdf
The presence of even small amounts of the ferromagnetic metals may thus show ferromagnetic properties.

@unionised: you wrote
Quote:
Yes, I have.
It was the electrode from a high power flash lamp.
Do you realise that your ignorance doesn't stop other people finding a use for it?
Incidentally, I also have a tin with 5Kg of tungsten sponge in it. It was chucked out as scrap so I git it for free. Not as valuable as a single rod, but quite a nice find.
Also, I rather suspect that they start with lengths of rod to make these.
http://www.google.co.uk/search?q=tungsten+darts&hl=en&am...


Both your electrode and the darts are probably alloys, not pure tungsten. It does not take much alloying metal to quickly reduce the density of W. I was referring to pure tungsten.
And yes, I do realise that my ignorance doesn't stop other people finding a use for things. Otherwise the world would have come to a stop long ago!

Your Archimedean idea is a good one. As a further demo of the principle I would add suspending the thread via a spring balance to show the effect of buoyancy, also showing where the apparent weight gain is compensated. Your idea is far more accurate than measuring the displaced volume of the liquid which I have often used.
The principle is very easily shown mathematically.

@ Erbium_Iodine_Carbon
I am still very skeptical (~4σ;) but congratulate you either way. This is either one of the best hoaxes ever perpetrated on the members of this forum or a really lucky find. You win both ways!

Der Alte
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