Can cast iron be used for making jam?

I've never made jam before, and before now, have never even considered making jam.

I've been told that, as with "fresh from scratch" tomato sauce, jam should not be made in cast iron, although you can use enameled cast iron.

I learned this when a lady became very upset because she thought her enameled cast iron pot had lost its enamel coating on the bottom; She thought that her pot was ruined, and she could no longer use it to make jam.

What really happened was, the pot became discolored on the bottom, and that always happens eventually from the normal cooking process. It was not exposed cast iron.

As I have never made jam, I can't yet comment on how it's made. But I am researching and learning, and plan to try it eventually in my enameled pot.