Silver Rosie and possible error weak mint mark 1970 D

[pokerbear]

The 1970 rosie on the right appears to have a very weak mint mark, the one on the left is a normal dime for reference. The possible error on the right is a sharper coin, yet the D is very faint, not like it is rubbed down but more like it was not struck solid. I can't find any info out there on the web about this error on this coin but have seen other error coins with weak mint marks, this seems to be one. Does anyone have any info on this type error.

Thank you
HH