I want you to discover the mortar set. Here are some references in Zoell's books 1944 - Zoell 2nd édition 1962 - H67d 1947 - Zoell 2nd édition 1962 - H70b 1947ML - Zoell fourth edition 1968 - H71n 1949 - Zoell fourth edition 1968 - HP73o 1950 - Zoell third edition 1965 part.2 - H74n 1957 - Zoell third edition 1965 part.2 - H81q Explanation: From Minor coin varieties -Third edition - 1965 part 2 - Hans Zoell page 15 ''MORTAR SET'' legend, ornamentation, etc., may be caused by chipping around the edges of the recessed portion of the die Good hunting and luck!
I have never heard of "mortar sets". Is there any value to these? It just doesn't appear to me to worth hunting. I may be wrong , but I think I have seen this happen on American coins too.
You can see 2 example at this link http://www.coinsandcanada.com/coins-errors-varieties.php at #9. For the value, I saw sell on Ebay between $ 5 and $ 15.