I purchased some ballast from Arizona Rock & Mineral and was half way done with ballasting the yard when I discovered that it contains a large amount of metal. More than 50% in fact. I was shocked. This is a product designed for model railroad use. I have been carefull about demagnetizing and sand or dirt I use but never thought I would have to check store bought ballast. Question is, What now? It doesn't seem to create any shorts but I'm concerned that my engines will pick up stay granulars that break free. Who else has run into this?