Nothing. Within a few days of releasing it, ABC withdrew the report. And that was the end of that there story.
There was no follow-up in the media about the bentonite discovery. Nor any follow-up concerning ABC's withdrawal.
Subsequently, another outlet reported that one of the scientists involved in the investigation said something akin to "In our analysis of the spores, we found a very surprising (chemical/substance/compound). It shocked us all."
And that was the end of that there story. The chemical/substance/compound was never identified. Nor was there ever any follow-up on this report, either.
I'd really like to know who told ABC to drop the story. My guess is that ABC's info was accurate.
By the way, I believe the active ingredient in bentonite, for purposes of deionization, is aluminum silicate.
That's far from clear, and even if it were clear it probably wouldn't help solve these crimes.
In order to produce inhalation anthrax, bacterial spore-particles must be small enough--no more than a couple or three microns wide--to reach a victim's lower respiratory mucosa. And for decades, until very recently, scientists believed that the mechanical milling required to produce such fine dust artificially would also produce a charge of static electricity sufficient to bind anthrax spores together into oversized, harmless clumps. To prevent this from happening--to keep the spores separate, "floaty," and therefore deadly--bioweapons specialists in the United States and elsewhere went to considerable lengths to identify a chemical additive that would, like throwing a sheet of Bounce into your clothes dryer, remove the static. It has been widely reported, but never confirmed, that American scientists eventually settled on silica. It has been just as widely reported, and more or less confirmed, that the Soviet and Iraqi biowarfare programs each at some point used a substance called bentonite, instead.
The Armed Forces Institute of Pathology has performed energy dispersive X-ray spectroscopy on anthrax powder recovered from at least two of last fall's letters and has apparently discovered trace amounts of silica, but no sign of aluminum, an element basic to the best-known and most common form of bentonite (montmorillonite). Based on this result, government investigators have concluded, according to the Washington Post, that "it is unlikely that the spores were originally produced in the former Soviet Union or Iraq." On the same basis, and getting similarly ahead of herself, Barbara Hatch Rosenberg has decided the spores were prepared by a rogue or sanctioned U.S. laboratory worker.
But the fundamental chemistry involved here cannot sustain such certainty. Silica, or silicon dioxide, is simple quartz or sand, the most abundant solid material on earth. "Bentonite" is the generic term for a class of natural or processed clays derived from volcanic ash, all of which are themselves mineral compounds of silica--and not all of which necessarily contain aluminum. In other words: Trace amounts of silica in an anthrax powder are consistent with the presence of bentonite. And the absence of aluminum from that powder is not enough to exculpate any foreign germ-warfare factory thought to have used bentonite in the past.
The FBI and Rosenberg seem also to have ignored what has been standard practice in U.S. biodefense, medical, and veterinary laboratories for most of the past thirty years: Work with virulent strains of anthracis in dried-spore, aerosolized form is virtually unheard of. Pentagon production of weapons-ready--and presumably silicate--anthrax powder was abandoned during the first Nixon administration. The U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) at Fort Detrick, for example, doesn't even own the requisite technology to manufacture dry aerosols; USAMRIID scientists, like their civilian counterparts, use only "wet" anthrax--which has usually been genetically altered or irradiated to render it non-toxic.