Please appraise: over 100 year old charcoal drawing of woman of Native American descent

This is a really unique and beautiful item. Behind a picture we received from my great grandmothers estate of my father and uncle when they were young, we found this amazing piece. Due to it's quality, we at first thought that it was an actual photograph, but upon inspection it became clear that it is actually a charcoal drawing! The subject is beautiful, an older Native American descent woman in a nice dress. The clarity of this drawing is just so amazing, it is still hard to believe it is not a photograph. We tried once to investigate the picture even more, but tore a small piece from the side of the paper (where no charcoal is). So we packed it back in the frame and just let it hang on the wall ever since. The frame I believe to be the original frame that the artwork was put into. It is wood with some support pieces on the backside of the frame. Around the frame, there is a molded substance that appears to be some kind of metal, maybe brass or even copper, I'm really not sure. We have not found any kind of identification marks on this piece as far as an artist or name of the sitter or anything, but believe it to be an older relative of ours, as we have some Native American ancestry. I wouldn't know why else we would have such a thrilling piece, really. The glass in the frame shows some impurities. The paper inside is torn a little from when we took it out, and there are a couple of spots on the edges where there is a small rip. The bottom of the artwork shows some damage from perhaps moisture but the area where the drawing is on is in good conditon. This has been an important treasure for our family for a while but if it were worth enough, we could compromise by making copies of the portrait which we need to do anyway and sell the original. We could use some help getting some businesses started or else we wouldn't think of selling this. If anyone has any idea how much this might be worth, I would really appreciate your opinion. The first thing I need to know I suppose is if this is worth taking to a professional for an appraisal also. We have thought about it but have not found a place yet or made any attempt. The picture's total measurements with the frame are 23 3/4" tall and 19 3/4" wide. Thanks and take care.