Question about tintype photograph

I believe this tintype is a photograph of my great great great grandmother. I'm quite certain that it was either taken in Germany or the U.S. It measures 3 1/5 inches X 2 3/8 inches (it is a wallet sized item). I'm wondering if you know of someone who could identify the approximate date of the picture and whether it was from Germany or the U.S. ? There are no markings on either side. I've enclosed both a small and blown-up version of the picture. Thank you in advance for your help.