Very thin and pliable, the sides were quite crumpled, but the bottom is fairly smooth and intact. Probably less than 1/16th inch thick. Historical context may be 1850-1880.
Black powder was at one time shipped and transported for use in lead containers (once emptied you had a source of lead for casting balls). But other things were as well.
After thinking about it a bit, I realized that this had to be the lining of another container. It wouldn't have been able to support itself without sagging, and it would have easily bent into creases and broken.