I was in one of my local Dollar Tree stores a while back and stumbled across these bags of decorative stones for flower pots, decorations, etc. This is the store where everything is a dollar so I thought why not. I picked up three bags to test them out. They come from China, which I usually avoid like the plague, but it is what it is. Processed them with a BFH and was surprised to find many of them threw pretty decent sparks. A couple of black pieces actually...Found A New Source For Sparky Rocks