In an effort to better understand the conditions that led to complete collapses of the World Trade Center
Towers and WTC 7, we apply scanning-electron-microscope (SEM) and energy dispersive x-ray
spectroscopy (XEDS) methods to analyze the dust generated, with an emphasis on observed micro-spheres
in the WTC dust. The formation of molten spheres with high iron contents along with other species in the
WTC dust required extremely high temperatures. Our results are compared with those of other laboratories.
The temperatures required for the molten sphere-formation and evaporation of materials as observed in the
WTC dust are significantly higher than temperatures associated with the burning of jet fuel and office
materials in the WTC buildings.b