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metals, alloys, compositions... help


8realesgt
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I was wondering if anyone has information whether it be webpage or personal on how to tell different metals, alloys, compositions apart on a coin?

 

Aluminum, Brass, Bronze, Chromium, Copper, Cupro-nickle, Gold, Iron, Lead, Maganese alloy, Nickle, Silver, Steel, Stainless steel, Tin, etc.

 

How do you do it?? I know it's done by weight in some cases but, what other methods are used?

I remember my dad braking a thermometer taking the mercury and I think testing the coin with it? Lighting a coin?, too.

I am asking this because although, I may guide myself by the Krause, Red book, etc. There are some that have different compositions (rare I guess)

 

Thanks :ninja:

p.s. guess I have to go back to school?

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Some of the metals are pretty hard to tell apart without metal testing kits. These work on different carats of gold and whatnot.

As for non-precious metals it generally becomes easy to tell by their weight.

Copper and bronze are somewhat difficult at times, but the deep/warm color of bronze normally gives it away.

Iron is magnetic.

Lead is soft enough to dig a fingernail into.

Tin and aluminum and zinc are lighter than most other silver metals.

Nickel is very hard compared to silver.

 

Not sure what else to tell you really. Why are you asking if you don't mind? Did you find one of these rare compositions?

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I remember my dad braking a thermometer taking the mercury and I think testing the coin with it?

 

Two things to consider.....

 

Mercury is very dangerous and can be absorbed through the skin and poison you!

Most metal testing kits for gold and silver use dangerous acids that can easily burn your skin.

 

I'm such a parent...

 

The easiest way to identify coins as genuine and to establish their metal content that I know of is with a good quality scale.

The new digital ones are getting cheaper and are very accurate. And the old balance beam models will still get the job done.

 

Pretty safe too, unless you leave your scale on the floor and trip over it in the dark... :ninja:

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Not sure what else to tell you really. Why are you asking if you don't mind? Did you find one of these rare compositions?

 

Thank you for the information.

No, I don't mind you asking..... I know very little in comparison with most of you about coins. I have been researching mostly via internet about some of the coins I have and bought the coin books my dad would have only recent versions of them. unfortunately, there is no "Red Book" on Guatemalan coins, which are the ones I mostly hold.

Yes, I do have some of the rare ones that my father marked as Ni, Cu, CUI, etc. trial pieces, proof (excuse my lack of numismatic terms as he left it in Spanish and is not always the same as in English, my knowledge is fairly poor). As he left many in holders, he also left stacks of coins in jars, unopened bags, etc. which he probably didn't have a chance to check as they are not in his inventory. And I have found in these bags some that I am uncertain about. Because of weight or color. Thus, my questions :ninja:

p.s. so there is a kit, that is what I thought...

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Mercury is very dangerous and can be absorbed through the skin and poision you!

Most metal testing kits for gold and silver use dangerous acids that can easily burn your skin.

 

I'm such a parent...

 

The new digital ones are getting cheaper and are very accurate. And the old balance beam models will still get the job done.

 

Pretty safe too, unless you leave your scale on the floor and trip over it in the dark... :ninja:

[/quote

 

Thank you for answering, I just had a giggle.... memories, memories... about the mercury, I wasn't allowed to be close when he did this. That is why I don't know what he would do with it.

 

I must buy the digital scale!! The one I have is the old balance beam, which is on a table not the floor ;)

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I had a look at your omnicoin, I am in love with those old Chilean peso coins, the oldest one I have is a 1933 cupro-nickel version. I do have a 1857 Chilean half decimo but that is about it. I think I just like coins with striking birds on them.

 

Anyway, the new digital scales are acurate to 0.01 of a gram, but cost around $20-50. I got mine for $0.01 but paid $24.99 shipping lol. Ebay, meh. Good luck figuring things out, and if you can't, post a picture here or the world coin forum and we will try to help!

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Yep - a scale and a Krause should go a long way as others have mentioned. You may also want to search on "specific gravity". It's fun to investigate and when I have compared the ratios of weighing a coin in and out of water (I am being a bit informal I guess), the ratios I get are very close to listed values for certain metals - although mixtures are more complicated. Still, you can add it to the list.

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Yes, I do have some of the rare ones that my father marked as Ni, Cu, CUI, etc. trial pieces, proof.....As he left many in holders, he also left stacks of coins in jars, unopened bags, etc. which he probably didn't have a chance to check as they are not in his inventory.

 

You should be excited being the caretaker of your father's collection, which sounds pretty exciting. Trial pieces? Proofs? NICE!

 

If you post photos here I'm sure some of the members will be able to help you identify what you have.

 

And don't worry about your English. It's easily as good as most Americans... :ninja:

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I'm not quite too sure what you are looking out for. In most cases, catalogs would have noted its weight and composition which is accurate most of the time. It's only when you get to trials where the weight is not documented properly which will be difficult.

 

I do have a wide range of coins in various metals and this includes platinum, palladium, tantalum and so on. Sometimes you really need to have the real thing in order to understand how a certain metal looks like. For example if I said raw platinum looks like stainless steel, would you believe me? :ninja:

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I had a look at your omnicoin, I am in love with those old Chilean peso coins, the oldest one I have is a 1933 cupro-nickel version. I do have a 1857 Chilean half decimo but that is about it. I think I just like coins with striking birds on them.

 

Thank you for your advice and for your compliment on the coins, am glad you like them, will post more pictures soon.....

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Yep - a scale and a Krause should go a long way as others have mentioned. You may also want to search on "specific gravity". It's fun to investigate and when I have compared the ratios of weighing a coin in and out of water (I am being a bit informal I guess), the ratios I get are very close to listed values for certain metals - although mixtures are more complicated. Still, you can add it to the list.

 

That I am not familiar with.... in water?? Hmmm... will investigate.... work, work, work

Thanks!! :ninja:

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You should be excited being the caretaker of your father's collection, which sounds pretty exciting. Trial pieces? Proofs? NICE!

 

If you post photos here I'm sure some of the members will be able to help you identify what you have.

 

And don't worry about your English. It's easily as good as most Americans... :ninja:

 

Yes, I am very excited about having my fathers collection, it is a lot of work and research. I don't mind, I just want to get it right and it has a lot of sentimental value, he really enjoyed collecting. I feel very close to him, specially when I read some of the posts from other members.... he was a good man.

Will post some more coins.... thanks for everyones help! ;)

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I'm not quite too sure what you are looking out for. In most cases, catalogs would have noted its weight and composition which is accurate most of the time. It's only when you get to trials where the weight is not documented properly which will be difficult.

 

I do have a wide range of coins in various metals and this includes platinum, palladium, tantalum and so on. Sometimes you really need to have the real thing in order to understand how a certain metal looks like. For example if I said raw platinum looks like stainless steel, would you believe me? :ninja:

 

You know, it's like a kid with a new car.... I have found some of the coins that were in bags on other planchets (as I said previously my numismatic terms might be off) and since some of these were made in different countries..... just makes you wonder?? I love the error coins.

Thanks you! ;)

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The problem with you question is that most methods to determine the metal of a coin or any object is the results would only indicate the outer service. Example the new Cents are pure Copper coated. Zinc is on the inside but a test on such a coin would indicate Copper due to that is what you see unless you cut it open. Brass and Bronze are really tuff ones. Note that Brass and Bronze are Copper with other additives. Brass is basically Copper=69%, Tin=1%, Zinc=30%. However, Bronze is a largely variable substance. Basic Bronze is Copper, Tin and various other materials in various proportions. Such additives are Phosphorus, Manganese, Aluminum and even Silicon. Our post WW2 cents were noted as Bronze due to being made from ammunition shell casings. The exact purity from back then is just a guess since there is a decent probability of many impurities being mixed in with every batch.

Even in our laboritories a spectroscopic analysis would only determine the outer material of a coin. Weight is a great method to determine a coins content but a good chemist could fool that system also. Further problems with weight is wear. The more a coin is worn, the more material is lost and that too makes weight identity difficult.

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The problem with you question is that most methods to determine the metal of a coin or any object is the results would only indicate the outer service. Example the new Cents are pure Copper coated. Zinc is on the inside but a test on such a coin would indicate Copper due to that is what you see unless you cut it open. Brass and Bronze are really tuff ones. Note that Brass and Bronze are Copper with other additives. Brass is basically Copper=69%, Tin=1%, Zinc=30%. However, Bronze is a largely variable substance. Basic Bronze is Copper, Tin and various other materials in various proportions. Such additives are Phosphorus, Manganese, Aluminum and even Silicon. Our post WW2 cents were noted as Bronze due to being made from ammunition shell casings. The exact purity from back then is just a guess since there is a decent probability of many impurities being mixed in with every batch.

Even in our laboritories a spectroscopic analysis would only determine the outer material of a coin. Weight is a great method to determine a coins content but a good chemist could fool that system also. Further problems with weight is wear. The more a coin is worn, the more material is lost and that too makes weight identity difficult.

 

Thanks for the help, I guess in a nut shell (if any) it comes down to the weight to determine the metal, since I am not going to cut the coin apart and have very little chemistry knowledge. My daughter did pull out a chart and tried to explain but, it was all in latin to me.... :ninja:

Yes, the brass, bronze and copper are the ones I am currently curious about. So they should all have different weight?

I will post some pictures in near future with its weight, hope you can all help as much as you have in this post.

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Here's a page with some definitions:

Click here

 

Great reference list!

 

I'm still suprised that coins are being made from tantalum. My only experience with this metal has been in the form of tantalum capacitors, which were popular in the 1980's in certain high-end audio applications. (I used to work in recording studios...)

 

Most electrolytic capacitors these days are made from aluminum and filled with an electrolyte, usually boric acid or sodium borate.

 

Tantalum capacitors had one big fault, besides delivering a brittle high end response. When they failed they would sometimes short and burn a large hole in the circuit board that they were soldered to. The smell was horrid and the circuit board was usually ruined.

 

That's enough electronics for now...

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Ego sum laetus... ;)

 

Sounds like you could do with some Latin help! :ninja:

 

I need all the help I can get, I feel so ignorant..... and I have yet, to post questions on Colonial and Byzantine coins..... ;)

I'll tell you a funny story......I was living in Arizona with my ex and he wanted me to meet his friends so, I did. One girl comes up to me and says, "So, you're from Guatemala....what do you speak there? Latin, right!" ;)

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I need all the help I can get, I feel so ignorant..... "So, you're from Guatemala....what do you speak there? Latin, right!" :ninja:

 

You know where to come if you need any help on English or British coins!

 

;) Would be quite funny if you spoke a dead language fluently!! ;)

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