process unknown

Hoping some of you curators of works on paper/process experts can help the silver-gelatin dummy. The above is a detail from a suspiciously photographic sized portrait (16x20"). I would guess late 19th early 20th C. The subject wouldn't have had a huge art budget. Any thoughts about process? The image is on a heavy piece of board. I'd guess charcoal but the Chuck Close realism leads me to think there is a photo somewhere in the image's past...