Is it Rust?

Hi all, my first post, and hope I can glean some knowledge.

I've washed, scrubbed, used straight vinegar, salt, Brillo pads, steel pads, and I still see what appears to be rust around the inside bottom edge of my skillet.

I'm beginning to believe that perhaps it isn't rust at all, but rather that it may be the raw cast iron. I have seen some new cast iron skillets that sport a brownish-orange, rust-looking color, and I'm wondering if this might be the case.

Only the edges appear bad, as the skillet has been seasoned in the past.

No amount of scrubbing I have done gets rid of it, so I am wondering: when a new unseasoned cast iron skillet is bought, what does it look like? Has anyone seen the type of brownish color on new cast iron as I mentioned above?

This isn't a new skillet, it is one my grandmother had used since the 1900s!

Appreciate the comments.

It may have been burned in a fire. This sometimes/often causes a red hue. Can you post pictures?

I believe this may show. I hope it's clear enough, if not, I'll repost.

Sorry, I don't see any red in that picture.

Clean bare cast iron is grey, so it has to be something else. I don't see fire damage, but the photo is too grainy to tell what it is we're trying to diagnose.

it's not red, it's more of a brownish orange around the bottom inside edge. And it's just around the edge, the rest of the skillet looks good.

I know the pic is grainy, but it's all I can do right now. Maybe I'll look for a digital camera somewhere.

Are you talking about the small patches just in the curve of the bottom inside?

Those look more like stains than rust.