These rocks safe?

[echoDreamz]

http://i279.photobucket.com/albums/...23-09/3-24-09Meputtingthemontractorbucket.jpg

I am not sure what kind of rocks these are, but I have TONS of them (note I just found this picture on the net). I have a ton in my backyard, does anyone know if they are safe? They are same rocks they use in ditches and drains.

Thanks!

 

[Rivercats]

Do the vinegar test by dropping a few drops of vinegar on the rock and see if it bubbles or fizzes (which my guess is that it will). If it does these rocks can raise your Kh, Gh, Ph alot and are not a good choice to use. Also another thing to consider is being in your yard you don't know what kind of chemicals they could have been exposed to and absorbed over the years.