What's the rule for rocks?

[thefirethief]

If you ever worried about whether the rocks that you have are chemically safe, its always an idea to quarantine them in their own bucket for a few days then test the water parameters. Althought thats not neccessary most of the time. Im led to believe most hard rock is fine as long as its cleaned and boiled.

 

[Rosemary]

Here's an article about how some rocks can affect the pH of your tank and how to test a rock to make sure it is okay for aquarium use: http://freshaquarium.about.com/cs/qa/f/faq0017.htm

Here is more detailed page about rocks for the aquarium:
http://www.thekrib.com/TankHardware/rocks.html
According to this page, marble is NOT aquarium safe.

Quartz is a common rock that is aquarium safe and very pretty, especially rose quartz and amethyst.

 

[Watcher74]

Rose quartz, amethyst, or any kind of quartz would look rather fake in an aquarium.

Depends on what look you are going for.