It was used in the preparation of ferric oxalate developers for dry-plate processes. You can find recipes that included "iron alum" (its pre-systematic name) and oxalic acid: the complex oxalate salts actually involved in development were formed in the bath.

I believe it can be used as an Fe(III) donor in various Van Dyke-like processes as well.

Regardless, the terms to look for in vintage formularies will be things like "iron alum" "ammonio-ferric alum", and similar terms.