I'm not an error collector but I do have a piece or two in my collection. I do have sub categories and I wonder where you list your errors? My choices would be either in my regular coin collection by it's type and date or in Exonumia. The same question would apply to my paper currency collection as well. I'm currently leaning towards Exonumia. Presently I have them under type and date. What's your thoughts?
I put mine under type and date. I consider exonumia to be things like medals, tokens, and other non-coins. Error coins are still coins.
Perhaps it would make a difference if I said what the error is. Although it started out as a coin, the banks probably would not keep it in circulation. It's a misaligned strike where only part of the coin shows. Fortunately the part that was stuck has the date on it. I'm thinking if anyone took the time to look, they may not want to accept it. Would you still include it in your inventory with other circulation pieces? I don't include commemoratives or bullion in this category either, even with a full strike and a declared value on them.
I have 2 off-center strike cents in my collection that I found roll hunting. They sound similar to what you described. Still a coin even if it isn't all there. In the end, it's up to you how you want to sort your collection. Do whatever works and makes sense to you.
any coin that was minted by a government is cataloged by type and date in my collection, exceptions to this are coins that have been altered, added to or damaged outside the mint or tokens an medals, they are listed as exonumia, silver or gold rounds/bars are also listed separately.
I think I'll let them sit right where their at, categorized by type and date. I was over thinking this too much. Thanks for the opinions.