http://georgewashington2.blogspot.com/2008/08/ivins-could-not-have-coated-killer.html As everyone knows, the government initially tried to blame Iraq for the anthrax attack. One of the claims made was that the anthrax contained bentonite clay, which was also used by Iraqi anthrax bioweapons makers to "weaponize" the anthrax by decreasing the tendency of anthrax spores to clump together. (Clumping makes them less deadly since clumping reduces the amount of spores which end up in the target's lungs).
The government later disclaimed that assertion. However, the FBI now claims that the killer anthrax contained silicon. Silicon can be used as an anti-clumping agent to weaponize anthrax.
For example, McClatchy notes:
"Some of Ivins' former colleagues also dispute the FBI's assertion that he had the capability to mill tiny anthrax spores and then bind them to silicon particles, the form of anthrax that was mailed to the office of then-senator Tom Daschle, D-S.D."
And as New Scientist writes, FBI agents "mention a 'silicon signature' for the anthrax in the envelopes with no further comment. Silica may be used to weaponise spore powders."
Evidence for the theory that the anthrax used in the attacks was coated with anti-clumping agents also comes from a a 2001 CBS article:
"When technicians at the Army biodefense lab in Fort Detrick, Md., tried to examine a sample from the Daschle letter under a microscope, it floated off the glass slide and was lost. "
Anthrax would normally clump, so the fact that it "floated off the glass slide" points to the anthrax being treated with anti-clumping and anti-static agents.
Why is this important?
It takes very sophisticated equipment and processes to coat something as small as an anthrax spore with anti-clumping agents:
"Only a sophisticated lab could have produced the material used in the Senate attack. This was the consensus among biodefense specialists working for the government and the military. In May 2002, 16 of these scientists and physicians published a paper in the Journal of the American Medical Association, describing the Senate anthrax powder as “weapons-grade” and exceptional: “high spore concentration, uniform particle size, low electrostatic charge, treated to reduce clumping” (JAMA, 1 May 2002, p. 2237)."
Indeed, the anthrax sent in the letters was coated with a very rare, high-tech glass polymer nanomaterial: