Aquarium rocks advise!

Hi also, so I bought this grey slate from my local aquarium shop first time buying it for my aquarium and I rinsed and cleaned it etc. Once I placed into my aquarium within a few minutes parts of the rock became orange/brown. Just wondering if this is normal or not! Thanks for help on advance!

I would watch your PH. Pyrite is common in some slates and when it oxidizes it can raise the pH in the water. The FeS2 decomposes in water in the presences of oxygen to Fe ions, and SO4 ions and Hydrogen ions. Essentially forming Sulfuric Acid. Sulfuric Acid is common in low concentration in many environments so is not necessarily bad for your fish. If your water does not become significantly more acidic it is likely ok.

Overall I don't think the rock will cause issues if the staining is just on the surface. The pyrite or iron depositions on slate is often only along the bedding or cleavage planes where the redistribution of minerals during the rock forming process occurs.

Did you use vinegar or jet water to rinse it off before putting it in?

Hey
The only way to check a rock is hydrochlorid acid. Vinegar and lemon juice aren't enough accurate.
Also you should have boiled it for a good sterilization, and filed it down to get rid of any roughness.

Slate doesn't affect water chemistry but the other things on it might. However, I doubt they will cause any issues.

Thanks for your help, much appreciated ordered a testing kit which will come in handy in the long run!

Slate maybe the main rock there, but slates can also contain metals.
In my neck of the woods, iron and copper were mined from slate and slate-like rocks.

Bruce Leyland-Jones said:

Slate maybe the main rock there, but slates can also contain metals.
In my neck of the woods, iron and copper were mined from slate and slate-like rocks.

Click to expand...

You're right in poiting it : copper is dangerous even deadly to invertebrates.