Well, on another thread, borgovan shared a beautiful toned Buffalo 5c he scored. So, that got me thinking (and you know how dangerous that can be...) For some reason, certain coin types are more "prone to tone" than others. For instance, there are some great Buffalo 5c toners out there, but fewer Shield and V 5c. Lots of toned Morgans, but almost no Peace. Which coin types are most likely to be found with great NT ? Why are they more prone to tone ? One expects different toning from different alloys... but even different types of the same composition exhibit different toning propensity. For instance, both Morgan and Peace are 900 fine silver, the rest copper. But Peace rarely NT, but many Morgans do. My guess - it is mostly related to the differences in the nature of minting or the design. It seems to me that once a coin has lost it's original surfaces due to cleaning or other abuse it has less chance at rainbow NT. It may re-tone, but not rainbow. Is that true ? If so, why ? What's happening on the surface skin / texture that prevents NT on cleaned coins ?
Thank you very much for the compliment! That coin is a monster. Jefferson nickels tone extremely nicely. In fact, I think I have seen beautiful toning on nearly every single date/mintmark combination of the series. Percentage-wise, I would say that the war nickels have the most toning, although these are difficult to find toned attractively. I don't think the design plays much of a role. I think it's the composition of the metal, mainly. In your example, you talked about Morgan and Peace dollars, but don't forget; there was only one Morgan dollar after 1904 (that being the 1921), so there's a large span between the Morgan and Peace dollar production. The metallic composition is largely different between these two series if you look at the trace metals involved. Once a coin is cleaned, I think it does not tone properly because of the microscopic geometry of the coin. The fluid flow-lines are gone, leaving less of a textured surface onto which the oxides would normally adhere. A smoother surface means less toning.
I thinkk the finish of the coin has something to do with it and with Morgans they had long storage times in bags that contributed to toning. Ruben
borgovan , you're right about Jeffersons , especially the proofs , seem to get that blue gray and gold rings , and you're probably right about the differences in the purity of the metal , but you would think with mostly 90% ag and 10 % cu they would tone pretty much the same , maybe the time does make the difference as I 've seen some toned Peace dollars . rzage
Peace dollars have a completely different finish than Morgans..different technology and they did't wash them the same. Ruben
It has to do with the metal the coin is struck with as well as the texture of the surface. With silver, the toning colors has to do with refraction through a layer of oxidation on the surface of the coin. The surface of the coin itself makes a difference in the refraction properties through the oxidation. Morgan and Peace Dollar's have very different surface characteristics which result in very different toning patterns.
IMO the major contributors to NT are metal type and preservation methods. The more reactive a coin's metal is, the more likely they tone. As I understand it the metals line up this way (from most to least reactive): 1. Copper 2. Silver 3. Nickel 4. Gold Copper mostly just goes brown. It tones easily but generally not in the rainbow colors. Silver is quite reactive too, but here the toning products are often in colors that appeal to many collectors. Nickel doesn't tone that well. I suspect the colors you see are a result of the copper in the alloy. Gold is relatively inert. I've never seen significant toning on a gold coin, especially not rainbow. Preservation does two main things for you. - Mechanical protection (dents, dings, scratches, etc.) - Chemical protection; it attempts to preserve the state of the surfaces of coins. If you get a rainbow toned coin and don't preserve it adequately, you end up with an ordinary toned coin.
Tell me more. Did the mint did keep records of trace impurities ? The official composition was 90% Silver, 10% copper. Is there some post-mint analysis of the alloys ? What are the trace metals, and how much ?
When a coin is cleaned, the radial "fluid flow lines" are gone... that makes sense. I can see why that permanently robs a coin of cartwheel luster. I'm not sure why that makes it less likely to tone, though I think you're right.
900fine: You may be interested in a book called "Coin Chemistry" by Weimar White. He goes into detail about the metallurgic analysis of Carson City seated coins in particular, but also speaks about toning overall. It's a great read.
I've got it too , but wish I payed more attention in chemistry class , that's why I swear by Intercept Shield 2X2s , your right a great read . rzage:whistle:
.900fine - this is an educational thread for me. Thanks for posting. Regarding the Morgan and Peace, could an additional factor (admittedly small) be time?
As has been said, the reason that Morgan and Peace tone differently is because of the surface of the coins being vastly different. Peace dollars have a much smoother surface than Morgans.
Here is an interesting thread that examines some of the specific surfaces for coins that tone more often that others. http://www.cointalk.com/forum/showthread.php?t=12578 Then you consider coins like the ASE Lehigh posted here: http://www.cointalk.com/forum/showthread.php?t=44175 And I posted Here: http://www.cointalk.com/forum/showthread.php?t=43368 And it changes my position a little on the first thread. The original surface prep of the Morgans and Franklin's seem to lend to very attractive toning naturally while Peace Dollars rarely tone. With coins like the next two (ASE and Matte finish 94 Nickel) outside influences like storage conditions can overcome the surface prep and cause any coin to tone. I have seen three more nickels like the one I posted since and they all have the same exact toning. I think it has to do with the material of the packaging??? As far as surface wear that borgovan talks about I think you have to consider more than just the surface. Chemicals, oils, and resulting environmental issues will cause toning and most of the time this toning is not very attractive. Still a subject I love to learn more about as my exposure to more coins continues. Despite some members dislike for toned coins I think we can all learn much from it.
Thanks ! I'm in. Easily available on Amazon and E-bay. Cheap, too... these coin books can be expensive. But not reading them is even more expensive !
VAM mentions that they flattened the fields in the Peace dies after the original difficulties with the 1921 / early 1922 trials. They also mention that Peace dies tended to stay in service longer. Did they use more or less striking pressure for Peace vis a vis the Morgans ? Or the same ? What made Peace surfaces so different ?
I believe the pressure was about the same. Die preparation made them different. Peace dollars have a more satinty luster than Morgans because the field areas were more polished. And about that book by White - by all means read it. But know this, most knowledgeable numismatist consider him to be just short of a nutcase and strongly disagree with his opinions.
'Originally quoted by Lehigh96' 'I agree that he is a nutcase' Hi Mr. Lehigh! As you know,this country has been founded on the basis that Every Man shall be created Equal and the right to Free Speech. You are entitled to your opinion just as I am mine. edited
