So, if this is part of your genealogy puzzle, you can be sure it was produced between 1855 and about 1865.
The ambrotype's life span was very short, wide-spread use was less than ten years, but produced a vast collection of beautiful images.
The ambrotype was packaged in the same manner as the daguerreotype, encased with a mat, top glass, and preserver; and then placed in a case. While the ambrotype is typically cased like a daguerreotype, it does not exhibit the same look. Rotating the image will not cause the image to reflect like a mirror or look like a negative.
Note: Don't mistake the reflection of the cover glass to be the mirror look.
Mats, the brass inner frame that laid on top of the glass, experienced design evolutions that are datable.