Oh yeah, I've always used it in my tanks. I have a huge two foot piece sitting out back that will probably be used for when I get a bigger tank down the line. As was mentioned above, some may be a bit jagged so just be cautious.
I can actually drive about an hour away to the desert and find some. The huge collection I have now came from Mexico, just across the border. My grandfather got them when back in the day you could just drive across anywhere you wanted to.
Just be sure to put some real wood in there if you have any plecos so you don't confuse them! (Hey this wood isn't real at all! What gives?)