Actually, the "tin" in a "tintype" photo is lacquered iron.
An earlier process, the ambrotype, was exposed on a small sheet of glass, and usually found in a decorative frame or holder to protect it.
Both types of photos were generally made in the 1800's.
Images below show some of the ones in my own personal collection. Presumably all are rather old.
The actual photos are rather dark, and to show the details of the people and settings, I lightened them up digitally for this gallery.