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Weird Purple Stain On Canada Gold Maple Leaf

 
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Author Previous TopicReplies: 5 / Views: 370Next Topic  
Pillar of the Community
United States
5513 Posts
 Posted 05/08/2021  2:25 pm Show Profile   Bookmark this topic Add Jaobler to your friends list Get a Link to this Message
I purchased this Maple Leaf in 2009. At the time I noticed the pronounced vertical "hairlines" on both sides. Careful examination shows these lines do not cross devices and they pass under, not over, the letters and digits in the legends. Therefore, I'm confident they are die polish lines and not evidence of abrasive cleaning. I put the coin in a soft plastic flip and stashed it in my safe deposit box.

I recently pulled it out and discovered a large purple stain on the reverse which had developed while the coin sat in storage. The stain was not present when I got the coin but the photo I took at the time does show a faint trace of what eventually became the stain. Here are current photos of the coin, plus the reverse photo from 11 years ago.

Gold is chemically inert and I would not have expected any toning to develop on a 999-pure bullion piece. Has anyone seen a similar problem on a pure gold coin? Any speculation about the cause? FYI, soaking the coin in acetone did not touch this discoloration.

Interested in your thoughts! Thank you!



Bedrock of the Community
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United States
58404 Posts
 Posted 05/08/2021  3:02 pm  Show Profile   Bookmark this reply Add Coinfrog to your friends list Get a Link to this Reply
Agree these are die polishing lines. Shame a bout the stain - I doubt acetone would help, but it might be worth a try.
Bedrock of the Community
Canada
10338 Posts
 Posted 05/08/2021  5:35 pm  Show Profile   Bookmark this reply Add JimmyD to your friends list Get a Link to this Reply
Never seen lines like that on a Gold Maple Leaf. That is supposed to be a satin background.
The mark is what is known as "Copper Spotting" which causes a reddish coloured stain
It is still worth an ounce of gold.
Pillar of the Community
United States
5513 Posts
 Posted 05/09/2021  2:01 pm  Show Profile   Bookmark this reply Add Jaobler to your friends list Get a Link to this Reply
JimmyD, I'm familiar with copper spots which are fairly common on gold-copper alloy coins. Incomplete mixing of the alloy leaves small areas with high copper content on the coin surface. The copper-rich spots then develop toning as the copper reacts chemically with the environment. A Maple Leaf however is 99.9+% gold. There shouldn't be enough copper or any other base metal present to cause spotting.

Frog, as you suspect a long acetone soak did nothing to affect the spot.
Pillar of the Community
United States
848 Posts
 Posted 05/11/2021  02:23 am  Show Profile   Bookmark this reply Add Cross-eyed to your friends list Get a Link to this Reply
Purple is the color of gold when coming out of solution.
Some where it must have had a drop of acid fall on it.
Do they use an acid in the die polishing room for some reason?

Valued Member
United States
57 Posts
 Posted 05/17/2021  01:50 am  Show Profile   Bookmark this reply Add glenmorenee to your friends list Get a Link to this Reply
Agree that those are die lines which appear to be common with the older MLs.

My experience is that red spots are not common but not uncommon either. Seen them on Buffaloes, some older Australian Nuggets and in particular Pandas. Haven't seen many on Krugerrands oddly enough.

Acetone is no help.

I am NOT saying to do this but this is what I've tried a few times and it works but is NOT a permanent solution. The spot will come back. If you check with a 10x loupe you'll see what I call a "seed" of foreign material, most likely copper of some sort. The lighter parts of the spot disappear easily and the darkest parts are more stubborn.


This is a Panda I did awhile ago. You can get one of those cheap cigar lighters on ebay or get a nicer tool that lasts a bit longer.



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