need help identifying mystery metal

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DylanDownright84

Well-known member
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Mar 14, 2017
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157
the owner of the small jewelry store i work at gave me a lump of a mysterious silvery metal. He could not tell me what the starting material was, but it looks as though it was on its way to being melted then stopped halfway. It does have some bluish, purple smooth crystalline under magnification in some spots.

I ran all the preliminary tests, neo magnet, scratch testing, no reaction with schwerters silver solution, 14k test solution, 22k test solution, or platinum test solution. All negative. When I got it home I broke off all the brittle pieces I could, about 7.5g worth and took it out to the shop. Put my propane torch on it to see if any tin, lead, solder would be visible, none, got it red hot, it kept its shape completely. Haven't used my acetylene torch yet.

I then took the pieces, added them to a small beaker, added a few hundred ml of 32% hcl and turned on my hot plate. After a few minutes there was a reaction.

Something was dissolving. The solution turned a beautiful lavender purple color after a couple hours on high heat, but no colloidal gold. Stannous negative, DMG showed a slight pink substance, nickel I believe, with some pieces no longer reacting, but reduced in size. Not sure whats being dissolved into the hcl. Just the transparent purple solution I've never seen before.

When I get more time either during the week or this weekend I will be further testing some of the leftover solids that didn't dissolve in hcl with dilute nitric and possibly some in AR.

If I'm forgetting a test or technique please chime in. He has two other pieces similar to this one, but they're much fuller, with almost none of the brittle parts like on this piece. They're quite heavy for their size. This piece was 45g. Ill measure and weigh the other ones and post those incase it may help. And thanks in advance!
 

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Try a few ml's of hot AR. After it reacts with the metal, collect the solution and test it with stannous chloride.
 
I did try a very small amount of AR and the solution turned from purple to yellow similar to a small amount of gold dissolved in AR, but reminded me of what iron looks like in AR. Negative stannous tests, negative DMG.

I'll have some more time to play around with it Sunday. I will check to see if I have access to an XRF through my jewelry contacts.

Thanks for the help guys!
 
jimdoc said:
My guess would be non precious dental metals. Lots of people think they are precious metals.
Click to expand...

That would be my guess as well

Note the blue rainbow color(s) on the blobs - which is the result of heating with a torch

Indicates the cobalt/nickel alloy used for making dental partial plates

Kurt
 
Got some updates. Went ahead and took Jeff's advice and put a small bit in AR. Solution turned yellow, negative stannous and DMG. Was left with a couple small shards of a very hard and jagged grayish looking metal that would not react anymore with the AR on high heat.

I took the small shards and put them into another small beaker with 50/50 dilute nitric on high heat and got no reaction after over an hour of heat. I'm going to try it in a more concentrated nitric solution next, but am expecting negative results as well.

The only other information I could get from my boss was that it came from a "guy who was melting contacts from something." And that this was almost a decade or so ago. So not much help. Hoping for an xrf test Monday while he's in NY. I posted some pics, but they're probably not much help. I will do some studying on the density test and see what I can figure out.

Thanks everyone! I really, really, really appreciate the help.
 

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Just attempted a density test.
Took a piece that was .49 oz divided by 16 making .030625 lbs.

In a beaker I put in 90ml of distilled water and lowered the piece in and saw a 3ml displacement. Water line rose to 93ml.

Im am unsure of the math past this point, but got .0102083333

Not entirely confident I did this correctly.
 
Testing for Specific Gravity - The classic method for the test is to start by weighing the item on a beam type scale. Then, a thin thread is tied to the item, it is suspended from a hook on the beam of the scale, and a container of water is placed on a support so that the item being tested is submerged in the water and the container does not touch the scale’s weighing pan. The weight of the water displaced by the item is calculated by subtracting the item’s weight in water from its dry weight. The specific gravity is then determined by dividing the item’s dry weight by the weight of water displaced.

Beam scales have been greatly replaced by today’s inexpensive digital scales, but the test is just as simple. Again, start by weighing the dry item and record the weight. Again tie a thin light weight thread to the item. Light weight monofilament fishing line works well as it does not absorb any water. Fill a small container with enough water to submerge the item. Place the container on the scale and zero the scale (if you can’t zero the scale, record the weight of the container). Hold the string over the container, lower the item until it is submerged (be careful to not let the item touch the container), and record the weight. Be sure there are no air bubbles clinging to the object as they will affect the result. This is the weight of the water displaced by the item (if you couldn’t zero your scale, subtract the first weight of the container of water from the second weight with the item submerged to determine the weight of the water). Divide the weight of the item by the weight of the water displaced to determine the specific gravity.

Dave
 
If my "calculations" are correct, it has appr double the density of Aluminum.
0.49 Oz(T)? ie 31.2gm/2 and a volume of 3ml will give a densty of 5gms pr ml or slightly over.

Cobalt at 8.9 and Mn at 7.5 needs to be mixed with something quite light if the alloy are to end up at 5ish.

I agree that the XRF might be best solution here.
 
Measuring volume by using the level change in a beaker is very error prone, use the scale and a small beaker with water in it, hang the metal from a thin string just as Dave described.

Göran
 
The following specific gravities of various metals are from Solids and Metals - Specific Gravities

Beryllium 1.848
Aluminum 2.55 - 2.8
Magnetite 3.2
Barium 3.62
Titanium 4.506
Antimony 6.69
Zinc 6.9 to 7.2
Iron, cast 7.03 - 7.13
Chromium 7.19
Manganese 7.21 - 7.44
Tin 7.31
Steel 7.70 - 7.8
Brass 8.4 - 8.7
Silver, German 8.58
Cadmium 8.65
Cobalt 8.71
Copper 8.89
Nickel 8.90
Molybdenum 10.22
Silver 10.50
Lead 11.35
Palladium 12.02
Rhodium 12.41
Ruthenium 12.45
Mercury 13.534
Tantalum 16.69
Gold, US coin 17.18 - 17.2
Gold, 22 karat 17.5
Tungsten 19.22
Gold, pure 19.32
Platinum 21.45
Osmium 22.57

Dave
 
Sorry Dave.
Probably had the skewed glasses on, I read Manganese :eek:

It was not ment to be precise anyway :wink:
 

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