I was out on a river today and collected some sand from a large sandbar. It is soft and most grains are sugar-sized. There are lots of small pieces of what I think is muscovite mixed in the sand. These pieces are clear and shiney in the sunlight, flexible, and most are 1-2mm in size. Would this sand be ok for rays? I plan on rinsing it well, sterlize it with bleach, rinse well again, and then dry it before adding to the tank.