Rocks From The River

[stanleo]

So I am doing a rescape on my 10gl shrimp tank and want to include some rock work. I found some very interesting rocks by the river that I want to use.
 
My plan is to scrub them thoroughly with warm tap water and let them soak for a few days in dechlorinated water. Is this good enough to clean them?
 
Should I do something more? I know not to boil them as they might explode.
 
I also found these blue-green colored rocks that look like slate, very thin. They were all around the river bank. They are brittle enough that I can just barely snap them in half. Are these rocks or could it be something man-made? Would those be safe to put in an aquarium?
 
Thanks

 

[SmexxyNick]

They're fine 

 

[Ny82]

Yeah just give them a scrub with hot water and they will be fine. I have roof slate in mine I found after a storm, I also have a branch in my tank I found outside, I soaked it, stripped it and put it in. It didn't do any harm  

 

[Voxcharm]

I boil small pieces of wood. My boyfriend came home to me doing it once and thought I'd gone insane ;-)