Author Topic: What is this metal?  (Read 3102 times)

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Offline RefrigeratorTopic starter

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What is this metal?
« on: May 05, 2021, 11:44:50 am »
Found this weird chunk of metal in the garage, no idea what metal it is.
All i know is that some 15 years ago when me and my brother were kids he told me that you rub this metal on the bench grinder stone to clean it.
But i doubt that's true.  ;D
The metal is non magnetic and feels quite dense. The structure is very crystalline and it's very brittle, the crystals are huge and very long.
It seems very resistant to tarnishing, this piece is many years old but despite dirt still has shiny spots where it was broken long ago.
I tried breaking a piece off with pliers but it seems the metal is quite hard and breaking a piece off is not that easy.
Once i managed to knock a corner off it revealed some very shiny metal underneath.
It leaves me wondering what metal or alloy of metals this is, my closest guess would be bismuth but i'm not sure.
I have not yet tried melting the metal.
Any guesses?  :)
I have a blog at http://brimmingideas.blogspot.com/ . Now less empty than ever before !
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Offline Robert Smith Eco Warrior

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Re: What is this metal?
« Reply #1 on: May 05, 2021, 12:15:40 pm »
Interesting.  :-//
 

Offline Andy Watson

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Re: What is this metal?
« Reply #2 on: May 05, 2021, 12:47:38 pm »
Could be many things! If it is a "wheel dressing stick" it will be a composite of a very hard material, e.g. tungsten carbide or even diamond, sintered into a solid block. Norten make a proprietry stick that has a grey-ish appearance - sintered boron carbide - look up "Norbide wheel dresser".
 

Offline Zero999

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Re: What is this metal?
« Reply #3 on: May 05, 2021, 03:04:11 pm »
Are you sure it's a metal? Did you measure the electrical resistance? Does it read near zero, when measured with a DVM set to Ohms? Note you might need to stab it quite hard with probes, to break the oxide layer.
« Last Edit: May 05, 2021, 03:05:43 pm by Zero999 »
 

Offline T3sl4co1l

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Re: What is this metal?
« Reply #4 on: May 05, 2021, 03:20:49 pm »
Can you get an idea of specific gravity (weigh it, weigh its water displacement)?  Does it dissolve in HCl or H2SO4?  NaOH solution?  And if so, what color is the solution?

The long crystals resemble either a cross section from the Van Arkel–De Boer process, or condensed/sublimated material.  I suppose it could be directionally solidified and fractured too.

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Offline RefrigeratorTopic starter

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Re: What is this metal?
« Reply #5 on: May 05, 2021, 04:07:06 pm »
Are you sure it's a metal? Did you measure the electrical resistance? Does it read near zero, when measured with a DVM set to Ohms? Note you might need to stab it quite hard with probes, to break the oxide layer.
Didn't need to stab at all, only the dirty spots resisted some but that's just because i had to poke through the dirt.
DMM beeps with very little probe pressure.
I have a blog at http://brimmingideas.blogspot.com/ . Now less empty than ever before !
An expert of making MOSFETs explode.
 

Offline RefrigeratorTopic starter

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Re: What is this metal?
« Reply #6 on: May 05, 2021, 04:11:17 pm »
Can you get an idea of specific gravity (weigh it, weigh its water displacement)?  Does it dissolve in HCl or H2SO4?  NaOH solution?  And if so, what color is the solution?

The long crystals resemble either a cross section from the Van Arkel–De Boer process, or condensed/sublimated material.  I suppose it could be directionally solidified and fractured too.

Tim
I'd have to find my scale first. Funny how i bump into it all the time but when i need it the damn thing is gone, nowhere to be found.
I boxed most of my stuff when renovating the lab so i'll go look in the boxes.
Buti agree, a specific gravity measurement would be a good start.

I have some battery acid on hand i'll try dropping a few pieces in, a great opportunity to try out my ebay test-tubes.
I have a blog at http://brimmingideas.blogspot.com/ . Now less empty than ever before !
An expert of making MOSFETs explode.
 

Offline RefrigeratorTopic starter

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Re: What is this metal?
« Reply #7 on: May 05, 2021, 04:39:12 pm »
The metal reacts quite actively with sulphuric acid since there's quite some bubbling.
The solution appears to remain clear besides some floaties at the top, which may be just dirt from the surface since i didn't clean the metal before dropping it in.
The reaction is undoubtebly between the metal and the acid, not the dirt because the reaction has been going for quite a few minutes now and seems to have only sped up.
I have a blog at http://brimmingideas.blogspot.com/ . Now less empty than ever before !
An expert of making MOSFETs explode.
 

Offline JohnnyMalaria

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Re: What is this metal?
« Reply #8 on: May 05, 2021, 04:47:58 pm »
Calcium? See https://www.wikiwand.com/nl/Calcium .

Burn a bit of the cleaned-up stuff and see what color the flame is. Compare to attached.
« Last Edit: May 05, 2021, 04:51:06 pm by JohnnyMalaria »
 

Offline RefrigeratorTopic starter

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Re: What is this metal?
« Reply #9 on: May 05, 2021, 04:59:43 pm »
Calcium? See https://www.wikiwand.com/nl/Calcium .

Burn a bit of the cleaned-up stuff and see what color the flame is. Compare to attached.
Well it's not calcium for sure, from wikipedia:
Quote
calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air
This chunk has been exposed to air for years.
« Last Edit: May 05, 2021, 05:23:14 pm by Refrigerator »
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An expert of making MOSFETs explode.
 

Offline T3sl4co1l

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Re: What is this metal?
« Reply #10 on: May 05, 2021, 05:10:13 pm »
Calcium oxidizes slowly in air.  Magnesium?  Neither is very heavy nor hard.

Suspecting something top-left transition metals, especially scandium, titanium, chromium, manganese, yttrium, zirconium.  And of those, titanium should give a pink to purple Ti(3+) solution in sulfuric, chromium blue or green I think (but colored in any case), zirconium probably doesn't react at all, and scandium is very rare indeed.  Manganese I think tarnishes more in air, but if not, may be a good candidate; it has a very pale pink color in solution, so it could be easy to mistake.  Zinc, aluminum and other right-side transition and common metals aren't hard enough.  Unless it's something really oddball like tellurium, which is also colorless in solution; but that's still not very hard, AFAIK.

We can certainly rule out iron, nickel and PGMs, which aren't colorless in solution, and besides iron, dissolve very slowly if at all in acid.

Once that metal stops bubbling much, if you can filter and neutralize it to get some hydroxide or carbonate (preferably use dilute NaOH, but baking soda will do), that may be informative.  Also if the hydroxide dissolves in NaOH (amphoteric), or changes color over time (oxidation -- for example Mn(OH)2 is very pale, but quickly oxidizes to the brown Mn2O3).

As for intermetallics, who knows; many of them are hard, but I don't know of any that are commonly made in a crystalline form like that.  Large crystals implies purity, and master alloys (often mixtures of intermetallics) don't need to be that pure.

Oh yeah and speaking of grinders, if it's so hard, it's probably going to be really hot when struck by a nice fast grinding wheel -- if it makes a bright shower of white sparks it's probably something like Ti or Zr, if dull red sparks it's probably something relatively inert, and if nothing at all it's probably not as hard as it seems.  (Failing a proper metallurgical hardness tester, you could do the good old Mohs test using assorted items around the house.)

Tim
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Offline RefrigeratorTopic starter

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Re: What is this metal?
« Reply #11 on: May 05, 2021, 05:45:40 pm »
Calcium oxidizes slowly in air.  Magnesium?  Neither is very heavy nor hard.

Suspecting something top-left transition metals, especially scandium, titanium, chromium, manganese, yttrium, zirconium.  And of those, titanium should give a pink to purple Ti(3+) solution in sulfuric, chromium blue or green I think (but colored in any case), zirconium probably doesn't react at all, and scandium is very rare indeed.  Manganese I think tarnishes more in air, but if not, may be a good candidate; it has a very pale pink color in solution, so it could be easy to mistake.  Zinc, aluminum and other right-side transition and common metals aren't hard enough.  Unless it's something really oddball like tellurium, which is also colorless in solution; but that's still not very hard, AFAIK.

We can certainly rule out iron, nickel and PGMs, which aren't colorless in solution, and besides iron, dissolve very slowly if at all in acid.

Once that metal stops bubbling much, if you can filter and neutralize it to get some hydroxide or carbonate (preferably use dilute NaOH, but baking soda will do), that may be informative.  Also if the hydroxide dissolves in NaOH (amphoteric), or changes color over time (oxidation -- for example Mn(OH)2 is very pale, but quickly oxidizes to the brown Mn2O3).

As for intermetallics, who knows; many of them are hard, but I don't know of any that are commonly made in a crystalline form like that.  Large crystals implies purity, and master alloys (often mixtures of intermetallics) don't need to be that pure.

Oh yeah and speaking of grinders, if it's so hard, it's probably going to be really hot when struck by a nice fast grinding wheel -- if it makes a bright shower of white sparks it's probably something like Ti or Zr, if dull red sparks it's probably something relatively inert, and if nothing at all it's probably not as hard as it seems.  (Failing a proper metallurgical hardness tester, you could do the good old Mohs test using assorted items around the house.)

Tim

I hit it with the angle grinder and there were absolutely no sparks that i could see.
Also it might not be as hard as i made it seems but when you're going at it with a pair of snippers it does appear harder than say lead or tin.
For the acid test i did manage to get some good purchase on one corner and peel some metal off.
Yes i said peel, the crystals delaminated and peeled off the main chunk it's so weird.
It's not titanium for sure since titanium creates bright white sparks, and it's not magnesium that much i can tell because i have some pure magnesium ingots and they don't weigh nearly as much as this chunk does.

I wonder can i just pour some of the acid solution into some ethanol and watch the color as it burns?
I have a blog at http://brimmingideas.blogspot.com/ . Now less empty than ever before !
An expert of making MOSFETs explode.
 

Online tszaboo

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Re: What is this metal?
« Reply #12 on: May 05, 2021, 05:48:01 pm »
I think it is pyrite. I also found a chunk when I was a kid, though the metal content was much less.
 

Offline Benta

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Re: What is this metal?
« Reply #13 on: May 05, 2021, 05:52:19 pm »
My guess would be cobalt.
 

Offline RefrigeratorTopic starter

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Re: What is this metal?
« Reply #14 on: May 05, 2021, 05:59:24 pm »
Some news!
Went to try the ethanol experiment but before that i noticed the acid solution was a little thicker than expected.
Actually it was not thick, turns out some clear white crystals precipitated out of solution.
It's some kind of sulfate/ite right?

Next i'll try pouring the acid off and mixing some ethanol into the crystals, maybe i can get some colour when it burns
« Last Edit: May 05, 2021, 06:02:48 pm by Refrigerator »
I have a blog at http://brimmingideas.blogspot.com/ . Now less empty than ever before !
An expert of making MOSFETs explode.
 

Offline asmi

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Re: What is this metal?
« Reply #15 on: May 05, 2021, 06:01:16 pm »
My guess would be cobalt.
Cobalt Sulfate solution has a red color.

Offline asmi

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Re: What is this metal?
« Reply #16 on: May 05, 2021, 06:02:51 pm »
Zinc? Do the flame test to see the color. Zinc would give blue-green color.

« Last Edit: May 05, 2021, 06:06:49 pm by asmi »
 

Offline Gregg

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Re: What is this metal?
« Reply #17 on: May 05, 2021, 06:03:36 pm »
It is probably zinc or a zinc alloy from the look of the structure along the broken sides and reaction to sulfuric acid.  Flame tests are often contaminated by sodium which tends to overpower the color of other elements unless they are quite pure.
 

Offline JohnnyMalaria

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Re: What is this metal?
« Reply #18 on: May 05, 2021, 06:08:59 pm »
I wonder can i just pour some of the acid solution into some ethanol and watch the color as it burns?

Maybe. The ethanol may burn with an orange flame (carbon) if you don't provide enough oxygen (like a yellow flame from a Bunsen burner with the vent closed vs. blue flame when open).

You could let some of the ethanol solution evaporate on a suitable utensil. If you cook with gas, just put some on the end of a stainless steel knife and place it in the blue flame.
 

Offline RefrigeratorTopic starter

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Re: What is this metal?
« Reply #19 on: May 05, 2021, 06:27:32 pm »
Adding ethanol really made the crystals crash out.
Burning the ethanol solution did not reveal much, other than some orange licks of flame, but those might be just an incomplete burn of the ethanol.
After the ethanol burned off there was no residue but the spot did smell pretty strongly of sulphuric acid.

I agree that it could be zinc, as i remember zinc is pretty dense and makes some large crystals.
I have a blog at http://brimmingideas.blogspot.com/ . Now less empty than ever before !
An expert of making MOSFETs explode.
 

Offline asmi

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Re: What is this metal?
« Reply #20 on: May 05, 2021, 06:38:46 pm »
I would also try making a hydroxide of that metal (Me + H2SO4 -> MeSO4, MeSO4 + NaOH -> Me(OH)n). Many of them have distinct colors and physical properties, which may help to identify the metal.

Offline RefrigeratorTopic starter

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Re: What is this metal?
« Reply #21 on: May 05, 2021, 06:42:22 pm »
I put a piece of the metal on an old blade, gave it a bunch of heat with my butane burner and only when it got super hot did i see the slightest lick greenish/lime/cyan colour.
So it's between zinc and antimony.
I have a blog at http://brimmingideas.blogspot.com/ . Now less empty than ever before !
An expert of making MOSFETs explode.
 

Offline T3sl4co1l

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Re: What is this metal?
« Reply #22 on: May 05, 2021, 06:46:42 pm »
Salts have poor solubility in ethanol so that doesn't say much.  Take a few grains and hold them in said flame; as they get orange hot, they should burst into green-blue flames.  Only zinc does this, the temperature and color being diagnostic.  (Cadmium is close, but has a different color, and its oxide is yellow.  Zinc oxide is yellow when hot, quickly turning snow-white on cooling.)

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Offline JohnnyMalaria

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Re: What is this metal?
« Reply #23 on: May 05, 2021, 06:57:31 pm »
I put a piece of the metal on an old blade, gave it a bunch of heat with my butane burner and only when it got super hot did i see the slightest lick greenish/lime/cyan colour.
So it's between zinc and antimony.

Make sure you run the control experiment with just the old blade :)
 

Offline drussell

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Re: What is this metal?
« Reply #24 on: May 05, 2021, 07:16:58 pm »
I put a piece of the metal on an old blade, gave it a bunch of heat with my butane burner and only when it got super hot did i see the slightest lick greenish/lime/cyan colour.
So it's between zinc and antimony.

Make sure you run the control experiment with just the old blade :)

Haha, I was just thinking the same thing. :)

The look and SG of antimony and zinc are pretty close (what, 6.75 vs. 7?), but my personal guess is zinc.   :popcorn:
 


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