But Metamars, there are several potential sources of magnetic chips in WTC dust that Harrit et al. all but ignore......
Here are a few:
* Dislodged protective paint: this would most likely contain micaceous iron oxide = kaolin + Fe2O3. This is consistent with the detection of Al and Si (in addition to Fe and O) in the chips. However, NIST suggests Tnemec red primer paint was in fact used on the WTC structural steel, and this brand of paint contains zinc chromate in addition to calcium aluminum silicates.
* Spalled duplex iron oxide chips from atmospheric corrosion of A-36 steel. NIST reported Ca and Si were incorporated in the loosely adherent oxide scales on the WTC steel samples it examined.
* Electromagnetic noise suppressor materials consisting of laminated Fe-Si-Al (oxides) deposited on polymeric sheets and used in many electronic devices that would have been prevalent in the Twin Towers such as: laptops, cellular phones, digital cameras, TV monitors, RFID devices, etc, ...