Define "leather?" And maybe define "frock" coats."
Not that I have ever (yet) come across. Much akin to leather kepis...
However, there is a 19th century evolutionary line where Natives "copied" in buckskin White frock coats often adding "hunting frock" capes fringe, quillwork, moose-hair embroidery or beadwork. That was picked up by trans-Mississippi Whites such as hunters and scouts. And military men as well- George Custer had several.
In gleichem Schritt und Tritt, Curt Schmidt
Not a real Civil War reenactor, I only portray one on boards and fora.
I do not portray a Civil War soldier, I merely interpret one.