I should have asked this in my last posts, but I forgot.
I have another chemistry question, but I don't want to break any rules. Is it acceptable for me to ask simply what the functional/chemical difference is between red iron oxide and black iron oxide? Are they interchangeable in...whatever project one might be doing?

Where are the rules for this forum? I've been looking through pinned threads and FAQs, and not finding them.

Thanks!