Copper Oxide on Quartz Crystal

[Clownphish]

This is an oddly specific question, but first off, I want to put some quartz in some crevices in my aquascape, because I saw that quartz was inert in water. I think it would look interesting, so I thought I'd test it out with this piece and another piece I have before I bought more, but I noticed a green layer on the bottom of this piece. I can only assume it's copper oxide and I know that copper is dangerous to a reef's inhabitants. The question is whether or not this amount of copper oxide is dangerous (How many copper ions is dangerous? How many copper ions can be released from copper oxide in saltwater?). I have a 75 gallon FOWLR (2 clownfish) with some turbo snails.

 

[Dan_P]

The absolute safest thing to do is avoid putting terrestrial rocks in a marine aquarium. Or find quartz without the copper contamination.