it comes from iron ore right?any random extra information would be nice.
Dont feel like reading all that, but its probably just all the gaskets and factoring coating burning off. Things usually have a weird small after getting heated for the first times.
The answer is there, right in your question. :)
Hematite is the best mineral to get iron from. BIFs (or Banded Iron Formations) is a good example of rock that has a lot of hematite. The rocks only have to have above about 18% iron content to be viable as ore.
