Aquarium rocks

[Keao_m]

How do I know what rocks would be safe to put in my freshwater aquariums? I'm not looking to buy any if I can find some around. I don't know anything about rocks such as the different kind. And how could I find out if the rocks are safe? Thanks.

 

[butterfly_koi]

Found these online. Honestly couldn't tell you what some of them are lol I have rose quartz in my tank

Crystalline Quartz
Amethyst
Citrine
Rose Quartz
Granite
Jade
Lava Rock
Microcrystalline Quartz
Chalcedony
Sard
Onyx
Quartz
Slate

 

[Coursair]

How do I know what rocks would be safe to put in my freshwater aquariums? I'm not looking to buy any if I can find some around. I don't know anything about rocks such as the different kind. And how could I find out if the rocks are safe? Thanks.

Testing Rocks
To test the composition of your rock, put a few drops of ordinary white vinegar on it. If it foams, it's calcareous, and will affect the hardness and pH of the water. Limestone is probably the most frequently encountered calcareous rock, followed closely by marble.

Another means of testing the effect an unknown rock will have on your aquarium is to fill a bucket with water from the water source you plan to use. Then test and record the pH, hardness, nitrates, and phosphates. Place the rock in the bucket, let it soak for a week and test the water again. If there are no changes, the rocks are not likely to cause a problem. If the parameters change considerably, I'd advise against using the rock in question.

Also:
http://www.ehow.com/how_5838701_test-rocks-aquarium-use.html