Many years ago when my parents went on a trip they brought home a bunch of rocks from the rogue river. They are black and white, and I think they have some metal in them, but I am not really sure on that. My mom has been using them in her landscaping it seems like forever and since I am getting ready to set up my aquarium I was wondering if anyone has used these, or has any idea of what their properties are. Are they safe to use in planted aquariums? It seems like most people have not seen them before, but I am hoping someone here has experience with them. After doing a google search I can't seem to find any info on them. Thanks!