Iron Ore?

[Westinghouse]

I needed more iron ore to keep things running. I have 150 sitting in my "star". Unfortunately It won't let me use them. The Mayor's house doesn't even high-light.

[YeOldeMan]

That means you need to apply them to an iron deposit. Preferably one on which you've already built a mine.

The background image behind the iron should look like a mine, I believe, (in your star menu).