No doubt, but presumably those non water things are all things that evaporate, so wouldn't get left behind then the rain dries. The rain would have to pick up s

No doubt, but presumably those non water things are all things that evaporate, so wouldn't get left behind then the rain dries. The rain would have to pick up something up on the way down for it to contain something that precipitates out. That could be dust or soot, I'm not sure what else, but any minerals would have to come in that way