silica coating
Norm Covert, a conservative former Fort Detrick public affairs officer] echoes what is widely reported by reputable scientists. The anthrax in the mailings, he says, was “highly bred, weapons-grade ... with a silica coating and a slight electrical charge so that each particle repelled the other ... each particle no more than five microns.” Ivins had neither the expertise nor the equipment to create such a sophisticated form of anthrax.