This is a Cabinet card of a young musician who appears to be ready to play her string instrument. She is dressed nicely for her photograph and is wearing a broach pin. I believe that her musical instrument is a violin but I am hoping a more knowledgeable person can leave me a comment to let me know for certain, what instrument this girl is holding. The photographer and the studio location of this picture is unknown.
THE CABINET CARD GALLERY 
This is my favorite photo here, just beautiful. What eyes!
It is either a violin or a viola, the only visible difference is the size.
Yes, it is a violin. The ‘broach’ she is wearing is actually a watch, as was the fashion in those days.