[BrotherMan]

I had a hiccup with all of the mechs. In a world that seems to be at the technological level of the early 20th century it seemed a large leap - a very large one even in a magical world of people who can control the elements. And also for large metal suits they were incredibly agile and mobile.

It was weird, dissonant.

Nevermind the incredibly unwieldy one made of the unbendable metal. I can't make you think differently about it. With the ability to utilize (by force or other) the abilities of all of the Earth Kingdom benders, I don't think mining for things would be difficult. How they find any particular metal may or may not be an issue. Without better knowledge of how bending works it's hard to say.

If you think about how Toph happened across metal bending itself, I'd think mining ventures might be similar. One would "feel" for a what they're looking for and bend the earth to get at it. Particularly adept earth benders might be able to feel platinum but be unable to affect it.

I dunno.