Totally fine that you don't agree. For a long time I didn't believe in crystal energy. To each their own. I'm glad you enjoyed the article regardless :)

As far as your question is concerned, personally I believe that everything emits frequencies based on the energy its come in contact with (walls, trees, air, etc.) so yes, I believe the sand would emit something because everything is always emitting something. It probably wouldn't have a metaphysical element to it, but energy would still be there. Same for granite.
I would assume that it would just continue to emit whatever its come into contact with. I feel like Earth (and the cosmos, and everything) are large balls of energy. Lol.