Yes its a chip, but more interesting than my error in naming it that is its similarity to coppercoins 1951D 1MM 036. Note there seems to be more tilting of the D. The mint mark looks to be slightly farther from the date. In addition the thickness of the D is much less than any other D for that year.
As you said the MM placement isn't correct. The 036 also has a distinct split serif on the lower upright of the MM. Your coin has an unusual IDB the center post of the D is higher in relief than the MM itself. This is probably what caused the unusual shape of the triangular IDB @ the upper left. The 50's had quite a few interesting MM errors. One right off the top of my head is the Winged 52D. There is record and photos of it in many different die stages of failure.
