Copper Plated 12 Point Type ID

How unusual. Maybe it was for a bit of extra hardness?

Possibly electroplated for duplication. A common practice in the days before the before. :o)

I believe this is your typeface as shown in the 1860 Boston Type Foundry catalog (Ornamented No._?_). I don’t know if it is original to the BTF, probably not. Here’s the link:
https://archive.org/details/condensedspecime00bost/page/n106/mode/1up

I also remembered seeing an advertisement for copper facing of type somewhere, and I managed to find it in my copy of the 1878 Pettingill Newspaper Directory. Here is a link:
https://play.google.com/books/reader?id=AVQJAQAAMAAJ&pg=GBS.PT16&hl=en

Digging a little deeper, I find that the Newton Copper Type Company (from the advertisement above) was quite prosperous in the business of copper-facing type. It began in 1851, and at times had branches in Cincinnati, London, and Paris. Apparently, copper-facing foundry type was not at all unusual among publishers because it extended the life of heavily used type; even Theodore DeVinne used it. The introduction of typesetting machines doomed the company, but it remained in business for 56 years, until 1907—Bob