Read other letters about this article
So, there was never any bentonite found in the anthrax. This is interesting. The first question I asked myself was, "Why not just put the bentonite in there? It's a pretty ubiquitous clay material used in drilling mud." But then, if you don't have access to Iraqi bentonite, why would you put Wyoming or any other kind of bentonite in the anthrax? Specifically, why would you want to leave a chemical or isotopic trace of anything except Iraqi bentonite? Well, the answer to that is that you can't get your hands on Iraqi bentonite, so it would have just been easier to lie to the press about Iraqi bentonite being in the anthrax.
So, what does that line of reasoning mean? I'm thinking that someone in our government or inside an oil or drilling company (ie, Halliburton) has Iraqi bentonite. That's just a hunch, but if they did, why not put it in there? Well, because again, it was probably easier to just lie to the press, plus if the FBI always suspected a domestic source, the last thing you would want to do is throw in a rare ingredient that would implicate more people in and outside the government.
Hope that helps. Keep digging Glenn!