[volatile]

I'd like to buy similar rocks but not sure what they are called. Are they available anywhere online within the USA?

http://www.adana-usa.com/images/gallery01/2.jpg

http://www.adana-usa.com/images/gallery02/3.jpg

 

[WibblyPig]

It looks like some sort of igneous rock (granite, basalt, etc.). Your best bet would be to go to a local landscape supply place and see what they have that you like.

I just took a walk in our construction yard and found several that would work ranging from purple to black to grayish-green. Just be sure to stay away from limestone as it will raise your pH.

 

[2wheelsx2]

It's difficult to tell from the scale of those pics, but they may be fine grained non-vesicular basalt. And WibblyPig is right, you can probably find very similar rocks in landscaping yards.

 

[retoid]

It looks like some sort of igneous rock (granite, basalt, etc.). Your best bet would be to go to a local landscape supply place and see what they have that you like.

I just took a walk in our construction yard and found several that would work ranging from purple to black to grayish-green. Just be sure to stay away from limestone as it will raise your pH.

At that note, any rock you pick up from a stone yard should be tested before added to an aquarium.
Place the rocks in a bucket of water for a week and test the water. I bought some rocks I was sure would not harm my tank but they leeched ammonia after testing. It was very minor but still.

 

[2wheelsx2]

At that note, any rock you pick up from a stone yard should be tested before added to an aquarium.
Place the rocks in a bucket of water for a week and test the water. I bought some rocks I was sure would not harm my tank but they leeched ammonia after testing. It was very minor but still.

Hmmm...sounds like you got some rocks with organics on it which rotted. I think soaking in a strong bleach solution would be effective and cleaning up whatever organics were on there, plus a good scrubbing with a brush.