# Plz Help Identify this Cube of Metal



## Vscience (Dec 15, 2021)

What is this little black cube? I found it in a FL in thrift shop trash bin. I have never been able to figure out what it is made of. 
It is approximately .75" cube shape. It appears to have been hand-cut so the sides are not perfect. 
It is unusually heavy for its size = 108 grams. 
It is not magnetic. 
When I scratched the black surface, it shows a shiny silver color. (see last photo)
I haven't a clue.  
Thanks everyone for your help!


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## orvi (Dec 15, 2021)

Look like lead hammered into the square shape. 

If you have some scale that count to at least two decimals, perform a specific gravity test. Look it up on YT, there are plentiful of videos explaining it. This could give you approximate density - which can be compared with known metals.
Or take it to the jeweller´s. If they have X-ray analyzer, they will very shortly give you an answer. They could charge you some buck for analysis, but many times they help people for free  

But if it´s soft (eg you could make a dent in it with knife), i will bet it´s lead. Look very familiar.


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## butcher (Dec 15, 2021)

Not all metals will form a black sulfide or oxide like silver does, it may or may not be silver, although
It very well possibly could be silver, and you can test it. or have it tested.

A few filings dissolved in dilute nitric acid then adding salt NaCl would indicate silver if a white cloud or salt appeared in solution. or a drop of nitric then HCl or NaCl on the bare metal looking for a white cloud to form in the drops.

Or with a drop of Schwerters solution on the clean metal will give a red reaction for silver.
A gold and silver dealer can test it for you, or a scrap metal buyer may have the ability to scan it with XRF (if loaded with a proper program for the metal involved)...

With schwerters solution, you can also get an indication of other common metals as they give different colored reactions to schwerters solution.

to make your own Schwerters solution: use about 20 grams of Potassium Dichromate, 22 ml of concentrated nitric acid (70%), and 7 ml of distilled water.
Pure silver turns bright red
sterling 92.5% silver turns dark red
80% silver gives a brown
50% silver gives greenish

Brass dark brown
Copper brown
nickel blueish
lead, or tin reacts to give a yellowish color

​


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## olawlor (Dec 16, 2021)

orvi said:


> Look like lead hammered into the square shape.


I agree. 

At 108 grams mass, the density would be between 15 g/cc for a 3/4" cube (as stated), and 10 g/cc for a 7/8" cube (as it looks on the ruler pictures). Lead's density is 11.3 g/cc.


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## stella polaris (Dec 16, 2021)

Looks like lead to me. Try to melt it. If easy to melt its most probably lead. Also how does your cut look now? If oxided again it points to lead.


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## orvi (Dec 16, 2021)

butcher said:


> Not all metals will form a black sulfide or oxide like silver does, it may or may not be silver, although
> It very well possibly could be silver, and you can test it. or have it tested.
> 
> A few filings dissolved in dilute nitric acid then adding salt NaCl would indicate silver if a white cloud or salt appeared in solution. or a drop of nitric then HCl or NaCl on the bare metal looking for a white cloud to form in the drops.


Lead chloride is also quite insoluble, i think this test, if positive, dont really tell the difference between them (for inexperienced eye).


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## butcher (Dec 17, 2021)

???
The tests are for silver not lead.

Well, an inexperienced eye probably should not be doing the test unless he knew what to look for, and understood some basic chemistry or safety.

I normally would not need a chemical test for elemental lead metal unless it was to distinguish between lead or bismuth or some other metal with similar physical properties.

I thought most any one can tell if they have lead in thier hands, so I did not focus on testing for lead,.

The test describe above was for silver not lead, for lead I would use other tests.

Such as can I cut it with a knife that rules out a host of metals, leaving the lead and a few others, if needed we can use other tests for lead...

Athough this test for silver can be done with lead (although I can not see why anyone would, as the difference in hardeness of the two metals makes it hard to confuse the two). Lead and silver are easily distinguished in the test for silver. You can tell it is not silver (lead will not make the familiar silver milk before precipitating like silver chloride, and we can further veryify with hot water washes...

Lead chloride will not make a white cloud as silver does, It can form an insoluble chloride, silver chloride is fluffy or milk or fluffy cloud that flows around easily in a moving solution, not like lead chloride which forms a more clear needle-like crystal that will stay on the bottom (where the fluffy silver chloride will float around in a moving solution)...

Say we have both silver and lead chloride as insoluble salts mixed together, the lead chloride is soluble in hot water silver chloride is not, once the two are separated (by hot water the washed silver chloride will turn purple to black in sunlight.
Lead chloride in the clear wash hot water, when cooled will form or pricipitate the familiar clearish needle like crystals of lead chloride.


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## butcher (Dec 17, 2021)

Lead is soft, not hard like silver, lead normally forms a passive oxidized crust on its surface when exposed to air the surface is normally a powdery gray looking color often white to a dark grayish, if the soft surface is scraped away it will expose fresh lead metal, a shiny white or silverish looking color but with a blueish tint.

Bismuth is also a soft metal, its oxidation can have a pinkish tinge it is also a silvery-white metal when scrapped, it is lighter than lead and will melt at a much lower temperature, where lead is soft bismuth is brittle and breaking it exposes a large crystal structure with a colorful tint of blueish peacock of colors.

Tin soft (harder but than lead) gives dull gray oxidation in air.

Pewter is harder than lead and oxidizes a darker dull gray color than lead (more closer to dull gray-black).
Lead is much softer and can be more easily bent in your hands, or deformed easier under a hammer than pewter (or bismuth for that matter) lead is more malleable.

Silver exposed to air oxidation, normally H2S, sulfur, or sulfides will give a black color to the surface of the silver.

Silver would be my interest if it was a hard metal with a white or silver color after the oxidation was scrapped away, that is why my mind focused on testing it for silver (after ruling out it being lead with my pocket knife).

Some other white metals, like zinc with a whitish-gray oxide (galvanized metals) or magnesium dark oxidation with a white powdery look, are also harder than lead, aluminum oxidizes with a light grayish color is also harder than lead, pot metal is a white metal with grayish oxidation, pot metals are soft but much harder than lead...

If the little cube was not silver, it would be of little use to me and I would not need further testing.


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## Vscience (Dec 17, 2021)

Following up with a question..... Do you think this cube could be tungsten (or similar) because the density seems to be twice that of lead?


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## butcher (Dec 19, 2021)

Tungsten normally does not corrode that much, how are you determining the density?


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## orvi (Dec 19, 2021)

butcher said:


> ???
> The tests are for silver not lead.
> 
> Well, an inexperienced eye probably should not be doing the test unless he knew what to look for, and understood some basic chemistry or safety.
> ...


I just meant it in the perspective of somebody who did not attempted these tests before. And you are right in every word  you clarified it perfectly.


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## orvi (Dec 19, 2021)

Vscience said:


> Following up with a question..... Do you think this cube could be tungsten (or similar) because the density seems to be twice that of lead?


Tungsten is hard, very hard compared to lead. How it was going with "poking" it with knife ? Does it make an easy dent ? This will clarify lot of things. If you can cut a piece/shaving of it with knife (applying some force), it is most likely lead. 
Measuring density by just taking rough dimensions of the cube will give you only very rough estimate. Taking a good graduated cylinder and submerging it under the water will give you more precise volume of the object, but still just rough estimate of volume. 
Specific gravity test could be the best one in the amateur setup. If you are aiming to proof the material based on density.


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## squiggles (Dec 19, 2021)

Looks similar to the lead cube that is hammered up ready for cupelling following the firing of a gold ore sample using lead, via litharge, as the collector for precious metals. Search fire assaying of gold for full details.


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