Hello all! I'm wanting to set up a shrimp breeding tank with the yellow Neocaridina. I was buying some decorations and grabbed some turquoise from a landscape place, then realized it may have copper in it which I know is supposed to mean death for invertebrates. I couldn't tell by what I was reading if *all* turquoise had copper in it or if some is iron based instead. This particular turquoise is pale green. Any thoughts on the safety of these stones?