Hello, the teapot is made of bronze or brass, the internal lining is silver because it is made of tin. This tin coating is made on copper, bronze and brass items, which are intended for use and not just decoration, to avoid poisoning with copper oxide.
Do you happen to know anything about it’s origin or age?
I have no idea of its origin, but based on the shiny appearance of the tin inside the teapot, I’d say it shouldn’t be very old, at most around 30 years old. But I think valid questions for you to ask yourself are whether where you live, in general, are the items national or imported? How did you acquire the bulé? The person had possessions, took a lot of trips and things like that, but I find it difficult to make bigger determinations.