Well, I had always assumed it was cotton. It seems more like a military/mac style jacket to me, and would therefore be heavy cotton, rather than leather. I’ve never detected a shine or sheen to it. But I have posed the question to the one person who should know. I await his response! As he is currently a very busy man, so an answer may not be forthcoming…but we’ll see. It’s an important question, sir! And one I may need to know for my Mastermind appearance! Lol