I was finally able to get together with the homeowner and gain access to take some pictures. Here they are.

I tested with RSR2000 and the spots themselves did not react but the stone itself did. Homeowner claims that when she was mopping with the Daily Clean, the spots would appear. When she stopped and started mopping with another product (Simple Green) that no other spots have appeared since.

What other suggestions or thoughts besides the Iron Out with distilled water? At what dilution should I mix the Iron Out?

Thanks for the feedback.

J