This tintype is unusual in at least two particulars, the most obvious being that it is the portrait of a black woman, the other being that it is likely an outdoor location (ivy as a backdrop is my guess) suggesting that it was taken by a traveling photographer.
Dating this image is difficult for a number of reasons: the books on fashions do not in any way represent people of modest circumstances no matter what their position in society; the means to have stylish, up-to-date clothes of excessive yardage or ornamentation was not often possible for a majority of citizens, nor would it have been socially acceptable; the economic and social circumstances of most black Americans was greatly depressed well into the 20th century, so few would have had the opportunity to be photographed in the first four decades after the invention.
My impression of this woman’s dress leads me to think it may well be between 1857 and 1870, but I cannot declare that for certain because there is so little published or in the photographic literature. It is possible that she was a slave, or even if taken after 1865, based on her dress and the probabilities, she was most likely a servant in a household. Occasionally one sees portraits of black women servants with white children in their care, but they are quite rare. We will never know if she had this portrait taken of herself.
The image is a little above average in size for a tintype; it does not have sharp focus anywhere and is not even average in quality for a tintype; the woman moved her hands during the exposure. As is my approach with tintypes, I have opened up the tonal range somewhat. This is one of the first photographs I ever collected.