Can I put Iron Pyrite in a freshwater aquarium?
As far as I know, you can't because of the metals in the rock. I know you can use slate, shale and granite. Put the rock in a bucket for a few days, then test the GH, KH and pH. Also try dripping vinegar on the rock, if it bubbles, don't use it.
pyrite is deffinently not good for the tank as it's flakey and breaks apart. so your fish might find it floating around the tank water and eat it then shortly die because they can't digest it. plus all the chemicals in pyrite would be devistating to the water's chemistry. gold is certainly better but not many people have nuggets of gold lying around. Your much better off with some kind of crystal or tumbled stones like quartz or amber. but If you want to use metal's stick with metals like steel, platinum, gold, silver, bronze, or scilicon. these are metals that hold together really tight on a molecular level and wont change the water chemistry of your tank into something harmful. even if it's a platinum/gold layered object it still a good choice. metals that are sure to kill your fish are pyrite and copper as they both do not have a strong molecular structure so they always give and take molecules from their enviroments.
Thanks guys,what if I could coat the pyrite with aquarium silicone, clear fingernail polish or something?
aquarium silicone would be ideal but you would have to make it smooth and even. fingernail polish will kill your fish in minutes.