Hiya, firstly I wanted to say what a great site and forum this is, I just lurked until now
but since someones calling for a geologist I thought I'd etter crawl out of my shell
Iron Pyrite (FeS2), reacts very readily with water (H2O) and free oxygen therein to produce Ferrous Iron (Fe2+) and with more time comes Ferric Iron (Fe3+). The by-product of both of these reactions is Hydrogen Ions and Sulphuric Ions. (SO4).
Here's the Ferrous reaction;
4FeS2(s) + 14O2(g) + 4H2O(l) ---> 4Fe2+(aq) + 8SO42-(aq) + 8H+(aq)
Followed by the Ferric reaction;
4Fe2+(aq) + O2(g) + 4H+(aq) ---> 4Fe3+(aq) + 2H2O(l)
The long and short of all this horrific chemistry
is that adding Pyrite to your fishtank will lower the pH drastically and sooner or later kill your fish. since they will afterall be swimming around in less and less diluted sulphuric acid over time.
I dont think the veins in that rock are Iron Pyrites, if you want to be sure what it is you can do various tests for me and I'll have a go at determining what you've got. Either way mineral veins in any rocks are on the whole caused by metasomatic heating events which leave metal rich veins in a rock. What I mean is, if a rock has veins in it other than just plain old quartz then it isnt a good idea to use it at all
Hope this helps a bit, perhaps I should update a bit and then post my suitable rocks for aquaria article?
Lotte***
