The photograph is in a case which opens up and has a plush velvet-like material on the left side. I think this is a daguerreotype and the case and the woman's clothing could provide some clues as to when the photograph was taken. Her jewelry looks metallic and looks like it was enhanced in the photograph. The photograph is behind a glass plate which is very reflective and a bit tricky to capture with my little digital camera.
The outer case looks like a Union Case which might date it to sometime in the 1850s or 1860s. A Union Case was a mixture (or union) of shellac and wood fibers that were pressed into a steel mold. The Daguerreian Society has some good information on the history of daguerreotypes.