I have a question for someone out there who may be able to help me. In 1967 Canada issued its now famous "Centennial Coin Set". Inside the set was a silver quarter featuring a Bobcat. Because of the rapid jump in the price of silver the coins issued in the first part of the year were of 80% silver while those issued at the end of the year were 50% silver. My question is this. Does anyone know the total weight of each of these silver quarters? I need to know the total weight not just the weight of the silver contained in them. Since the silver difference cannot be detected by the naked eye I figure that it could be weighed and that would reveal the different coins. If anyone could help I would appreciate it. catman
To be honest I don't know since I'm not a collector of Canadian. One would think the lower silver content coin should be thicker or slightly larger. But consider this - the specific gravity of silver is 10-12 depending on purity. The specific gravity of copper is 8.9+. So .800 silver would be roughly the same as copper which would explain the same weights.
If you really want to find out, get a pre-66 (.800) and a 1968 silver (.500) quarter, drop those, then drop the 1967 in comparison to match the "ping" of the silver coin dropping on a table. BTW, I believe all of the coins in the gov't PL and Specimen sets are .800, being issued early in the year.
Ccgnum,there is a way that you can tell the difference in fineness of the Canadian Confederation Centenary 25c. coins by sight.The catch is you have to have well circulated examples of the coins. The colour of the coins provides the clue.If the coin appears whiter,then it is the .800 fine (or 80%) silver coin.The .500 fine silver coin has a very dull colour.The same rule of thumb applies to the 50c. coin as well,but I am not sure about the $1 though.
The specific gravity of 800 fine silver is 10.18 gm/cc and the specific gravity of 500 fine silver is 9.7 gm/ccso the 500 fine coin would have to be 5% thicker in order to weigh the same as the 800 fine coin. But it isn't possible to measure the "thickness" of a coin in any meaningful way. It might be possible to tell them apart using the "tissue paper test". If you take a known 800 fine quarter and a 40% silver bicentennial quarter and put the coin in queastion between them and then place a single layer of tissue paper over them. The fineness of the coin in question should be readily apparent. Silver is the most reflective of all metals reflecting from 95 to 98% of all the light that hits it. The higher fineness quarter will reflect more light back up through the tissue paper and appear brighter. So if the coin is just slightly brighter than the bicentennial quarter it is 500 fine, if it is a bright as the known 800 fine piece then it is 800 fine. (The greater the alloy the less light reflected.
I looked it up,the same rule of thumb applies to the 10c. coin,not to the 50c. & $1 coins.I didn't have the correct information though.
Color varies. I don't like it as an indicator since it's okay for lightly circulated examples, but once you get to VF or lower grades, the toning on most coins will throw away the ability to use the dark/lightness of the coin.
The problem is Roy, what have you really measured? If the high points on the design are opposite each other you can get one figure, if they aren't you get a different one. A weakly struck piece will give you a different figure than a strongly struck one. For example look at 2004 nickels. The planchets used at Denver and Philadelphia are same diameter and thickness. But after striking a roll of Denvers is "two nickels" longer than a roll of Philadelphias because the Denvers are struck at a higher tonnage and have the rims struck up higher. So trying to measure the thickness of the final coin can't give you good information about the thickness of the original planchet unless you made point thickness measurements at a few dozen points and averaged them.
