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V 1.41
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Background Attack Aftermath Evidence Misinformation Analysis Memorial

Aluminothermic Residues

Form and Composition of Dust Particles Indicates Aluminothermics

iron-rich microspheres
A micrograph published in a USGS report shows iron-rich spheres in the dust produced during the WTC's destruction.

Scientific studies of dust fallout of the World Trade Center destruction conducted within months of the attack contain a wealth of data about the dust's distribution, physical forms, and chemical composition. Although this data raised a number of interesting questions -- such as how the dust came to contain high levels of iron, aluminum, sulfur, and barium -- it remained mostly unexamined for years. Even FEMA's disclosure of profound corrosive sulfidation of steel members failed to elicit follow-up studies by official bodies, with NIST avoiding the subject entirely.

It would take a scientist working without the benefit of a government stipend to provide a plausible hypothesis answering questions about the dust and corroded steel: Steven E. Jones.

Iron-Rich Spheres

Evidence collected by the US Geological Survey (USGS) showed up in a 2005 report: photographs showing particles with striking spherical symmetry, ranging in diameter from under 100 microns up to about 1.5 millimeters. 1   Another set of reports, prepared for Deutshe Bank in late 2003 also shows micrographs of iron-rich spheres. 2   3  

Jones obtained WTC samples from several locations, including an apartment of a witness to the attack located across the street from the South Tower, and found spherules like the ones in the USGS photograph. His analysis showed that the spherules consisted primarily of iron, aluminum, sulfur, and oxygen. 4  

I collected iron-rich particles in the dust by pulling a magnet across the outside of a plastic bag containing the dust, pulling upwards to the top the magnetic material and pulling this aside for further analysis. These magnetic particles were, as one might expect, rich in iron. There was a surprising amount of this iron-rich material. Although others have reported the presence of iron-rich particles in the dust, I was surprised to find the abundance of spherical particles in this iron-rich component some of which were considerably larger than previously reported. It was exciting to me to find for the first time iron-rich spheres up to about 1.5 mm in diameter in a 32.1-gram sample of dust.

The iron-rich component of the WTC dust sample was analyzed in some detail by scanning electron microscopy (SEM) and x-ray energy dispersive spectroscopy (X-EDS). Using the scanning electron microscope, we found that much of the iron-rich dust was in fact composed of roughly spherical particles ­ microspheres [sic]. The presence of metallic microspheres implies that these metals were once molten, so that surface tension pulled the droplets into a roughly spherical shape. Then the molten droplets solidified in air, preserving the information that they were once molten in the spherical shape as well as chemical information.

Iron melts at 1538ēC, so the presence of these numerous iron-rich spheres implies a very high temperature. Too hot in fact for the fires in the WTC buildings since jet fuel (kerosene), paper and wood furniture ­ and other office materials ­ cannot reach the temperatures needed to melt iron or steel.


Jones searched for prosaic explanations for the metallic spherules and ruled out various scenarios such as their production from remains of the crashed aircraft. What he and fellow researchers found is that the spherules are best explained as a residues of aluminothermic incendiaries -- a conclusion that, like other diverse pieces of evidence, is consistent with a theory that thermite or its variants were involved in the destruction of the Towers.

metals in dust
Illustration from USGS report with the caption reading, in part: "Map of lower Manhattan showing (as stacked bar charts) variations in concentration (in parts per million) of some predominant trace elements of WTC dust and girder coating samples. Dust samples collected indoors are indicated by the single hatch pattern and girder coating samples by the cross-hatch pattern; all others are dust samples collected outdoors."

Residues Consistent With Incendiaries

Analysis of the chemical composition of dust samples provides further evidence of aluminothermic arson. For example, dust samples contained particles with high levels of manganese, zinc, and barium. 6   Barium is a toxic metal used in a number of industrial processes, but unlikely to be present in significant quantities in an office building. It is, however, useful as a catalyst and accelerant of aluminothermic reactions. Zinc, barium and sulfur are all common in military thermites. 7  


1. Particle Atlas of World Trade Center Dust, pubs.USGS.gov, 2005
2. Damage Assessment 130 Liberty Street Property, RJ LeeGroup, Inc., 12/2003
3. Signature Assessment 130 Liberty Street Property, RJ LeeGroup, Inc., 12/2003
4. Extremely high temperatures during the World Trade Center destruction, JournalOf911Studies.com,
5. Revisiting 9/11/2001 -- Applying The Scientific Method, Journal of 9/11 Studies, 5/27/07
6. Chemical compositions of the WTC dusts and girder coating materials, USGS.gov, 2001
7. Patent 6766744: Description, dodtechmatch.com,

page last modified: 2010-08-19