| Author |
 Replies: 114 / Views: 9,159 |
|
|
|
Bedrock of the Community
Australia
21786 Posts |
The coin could? be plated, but not necessarily so.
As most know XRF only examines the surface, and so weight can be a very useful help to back up other findings, or help to prove plating.
All testing should be taken together to have a better chance to get to the right explanation.
|
|
Valued Member
 United States
108 Posts |
Plating was the first thing that crossed my mind. In fact, the coin was in a 2x2 holder labeled, "Gold Plated". If so, the next questions is, with what? Not gold, because that would show up with an XRF scan.
|
|
Valued Member
United States
108 Posts |
My son also put a tiny scratch on the edge (I know, ouch!) and the color goes uniformly below the surface.
|
|
Valued Member
United States
108 Posts |
I did some quick calculations, and if the dimensions remain true to an original Lincoln, the weight (or mass, lol) should be 2.90 grams. If plated, of course, the weight would be in excess of 3.11 grams.
When the cent comes back I may remove from the PCGS holder and take it to work for an accurate weighing.
|
|
Pillar of the Community
United States
4691 Posts |
|
|
Valued Member
United States
108 Posts |
Thanks, Jim. I had not seen this piece. The plot thickens!
|
|
Pillar of the Community
United States
4691 Posts |
If you crack it out, specific gravity will help determine whether or not it is plated. If you live near a University, they may be able to perform that for you, rather than attempt it yourself (although it is relatively straighforward). Add: if performed by immersion in water, it is important to rinse in acetone and carefully dry it immediately thereafter.
Edited by jimbucks
11/09/2022 2:17 pm
|
|
Valued Member
United States
108 Posts |
Great idea with specific gravity.
|
|
Pillar of the Community
United States
4691 Posts |
Quote:
Great idea with specific gravity. If you decide to do this yourself, I can write a simple procedure for you. It really is a simple process if done correctly. |
|
Pillar of the Community
 United States
6535 Posts |
Quote:
If you decide to do this yourself, I can write a simple procedure for you. It really is a simple process if done correctly. Let's hear it. I would like to know  |
|
Valued Member
United States
108 Posts |
Edited by philoponus6
11/09/2022 2:43 pm
|
|
Valued Member
United States
108 Posts |
The specific gravity of 95% copper+ 2.5% tin + 2.5% zinc is 8.78, whereas the specific gravity of the alloy from the XRF scan is only 8.28. Both tin and zinc have specific gravities in the 7 range, not much different than copper, so varying the zinc/tin ratio will have negligible affect.
I assume if plated, the specific gravity would not change much, since the plating would be a small percentage of the overall composition. One exception would be a very dense gold, but we can rule that out.
There is enough of a difference that a simple test with a scale that measures to the nearest 0.01 gram should be able to differentiate between plated copper and the alleged XRF alloy.
Edited by philoponus6
11/09/2022 7:39 pm
|
|
Pillar of the Community
United States
4691 Posts |
I presume the S.G. from the XRF scan is calculated based on percentages of metal. If plated, it is calculating based on surface. A measured S.G. would answer whether or not it is plated. The calculation of S.G. based on the XRF scan is simple, but what's the point if it is indeed plated. Weight may be conclusive, the OP may have done the calculations to conclude if so.
Edited by jimbucks
11/09/2022 7:58 pm
|
|
Pillar of the Community
United States
2869 Posts |
Does it say anything on the exact alloy that was used in the tungsten patterns?
|
|
Valued Member
United States
108 Posts |
Yes, the calculations show nothing, apart from checking these calculations against a measured specific gravity. I even ordered a better coin scale on Amazon to do this. I should have the coin in hand and the scale early next week. I do wonder where the author of that short piece got his info on Tungsten patterns. Thank you so much everyone for your interest and input! Edited by philoponus6
11/09/2022 8:34 pm
|
| |
Replies: 114 / Views: 9,159 |
First Page
Posted 11/09/2022 05:02 am
