Is Natural Clay okay to put in your fishtank?

I was hiking and found some a creek with clay along the creekbed. I collected about a pound of it thinking I could put it in my fish tank. I was wondering if it was dangerous to the fish or since it was from a creek it would be perfectly fine. Thank you in advance.

Comments on "Is Natural Clay okay to put in your fishtank?"
More: Dogs or cats? Buy german shepherd? If you remembered all of your dreams how much would you pay for the perfect dream pet.? Why are my gold fish hiding at the bottom of the tank? I want my cat to be everything he can be in life. I want him to realize his dreams. How can I help him so that he will be proud of me?