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Posted 09/11/2025 5:10 pm
I think the issue is a misnomer.
Ottawa and Philadelphia 10-cent coins are indistinguishable. What we have there are different collar types. And there are more than 2.
I imagine that the autohr(s) of the original story were scratching their head trying to find any difference. They noticed the difference in the groove shapes and declared that Phily Mint had used US Dime collars. That was a mistake because US Dimes have collars with a different number of reeds and the shape of those does not match any canadian 10 cent.
The error made into Charlton and thus got perpetuated.
Some years ago I did a study and have found different groove shapes on 10 cents going as far as 1960. I did not extend the study to earlier dates.
The prevailing type from 1960 to 1965 was one with flat bottoms and flat tops close to rectangular in shape. Though some coins have a more trapezoid shape.
In 1965 (while preparing to nickel coins) a saw-tooth shape was introduced, which turned into "scalloped" as the collars wear off.
I see that difference between TT-10.2A and TT-10.2B, though my sample is too small to call it true difference.
The flat bottom trapezoid collars (as on the photo at the top of this topic) were the common type for 1966 and 1967, but V-shaped (almost triangular) examples exist.
!968 had seen both flat-bottom and V-shaped grooves on all types of coins - silver, Nickel BS, Nickel PL.
All my 1969 samples are flat-bottom, and in 1970 again both types are present.
Thus, the groove shape does not work as a mint mark.
I think there is a difference which I did not study when I had a big sample. It seems that all Ottawa mint coins (BS, PL) have a rounded edge with groove/reeds having a slope toward the coin planes.
Philadelphia coins have a square edge with grooves reaching into the rim. My current sample is too small to make a conclusion.
Ottawa and Philadelphia 10-cent coins are indistinguishable. What we have there are different collar types. And there are more than 2.
I imagine that the autohr(s) of the original story were scratching their head trying to find any difference. They noticed the difference in the groove shapes and declared that Phily Mint had used US Dime collars. That was a mistake because US Dimes have collars with a different number of reeds and the shape of those does not match any canadian 10 cent.
The error made into Charlton and thus got perpetuated.
Some years ago I did a study and have found different groove shapes on 10 cents going as far as 1960. I did not extend the study to earlier dates.
The prevailing type from 1960 to 1965 was one with flat bottoms and flat tops close to rectangular in shape. Though some coins have a more trapezoid shape.
In 1965 (while preparing to nickel coins) a saw-tooth shape was introduced, which turned into "scalloped" as the collars wear off.
I see that difference between TT-10.2A and TT-10.2B, though my sample is too small to call it true difference.
The flat bottom trapezoid collars (as on the photo at the top of this topic) were the common type for 1966 and 1967, but V-shaped (almost triangular) examples exist.
!968 had seen both flat-bottom and V-shaped grooves on all types of coins - silver, Nickel BS, Nickel PL.
All my 1969 samples are flat-bottom, and in 1970 again both types are present.
Thus, the groove shape does not work as a mint mark.
I think there is a difference which I did not study when I had a big sample. It seems that all Ottawa mint coins (BS, PL) have a rounded edge with groove/reeds having a slope toward the coin planes.
Philadelphia coins have a square edge with grooves reaching into the rim. My current sample is too small to make a conclusion.
