Ambrotype of Avant-Garde Woman

The woman shown in this 1860's ambrotype defies the norms of her time. Her dress is unconventional, and her hair is downright non-conformist. It would have been considered highly inappropriate for a woman of this era to wear her hair down. So, what's this unusual lady's story? I wish I knew precisely, but I can only speculate. The writing on the photo's case is sloppy, but it looks like it reads "Mademoiselle." There's a name after that but it is illegible. Was this woman a lady of the evening? An actress? An opera star? A gypsy? If anyone out there in the blogosphere knows the identity of this mysterious lady, please share it! Image is hand-tinted, 1/4 plate sized.