Over a year before the 2009 Bentham paper was published, Mark Basile made the discovery that certain 9/11 WTC dust chips consistently ignited at ~430C and produced iron-rich micro-spheroids in their residue.
His initial research of selecting, cataloging, photographing, heat testing, residue examining, and referral back to catalog notes and photo images, became more focused when he discovered that some chips showed remarkable thermitic behaviour.
At some point it became clear that the chips which ignited at ~430C and produced iron-rich micro-spheroids in their residue, were "readily discernible by eye due to their distinctive color.".
We know that chemist Mark Basile shared his findings with other scientists performing research on the 9/11 WTC dust.
They shared a common agreement about what they had observed and it became part of the 2009 Bentham paper.
MM