Why does a Canadian ounce weigh more than a US ounce? 0

[jtryka]

So today my "Pride of Two Nations" set arrived, and the coins are quite beautiful, but my question came when I reviewed the little booklet that came with the set which you can see in the photo below.  In it, the Silver Eagle contains 1.000 troy ounce of silver, or 31.103 grams which is correct from what I've been able to tell.  But the Canadian Maple Leaf is listed as containing 1.000 troy ounce, or 31.39 grams.  They are both pure silver, so I can't think there would be an alloy issue (like with gold eagles that are only 22 karat and hence the 1-ounce coin weighs more than an ounce to get a net 1-ounce weight).  Anyone have any idea why this would be, or perhaps it's just a typo?

 

Edited July 10, 2019 by jtryka

[Just Bob]

It is not a typo, since the earlier one ounce Maple Leafs were a!so 31.39 grams. My best guess would be that they are slightly heavy intentionally,  so that even an underweight planchet, if within tolerance, would still contain one full ounce of silver. 

Of course, that is just a guess, so take it with a grain of salt.

[Mohawk]

I've been thinking about this one all day and I have a theory....it may be total BS, and I'm fully prepared to hear that but here it is:

I know that the ASE isn't as pure as the ML, and I also know that the ASE does have a small amount of copper alloyed in it.  Copper is lighter than silver and the ML would have less copper and more silver in it than the ASE.....it's a minuscule weight difference so maybe the tiny little bit more copper that the ASE has it makes it lighter by a tiny amount.