This 12 minute video by someone calling himself "HAARP Report" claims that the source material for chemtrails is coal ash or fly ash. Some of his reasons: It has substantial percentage of aluminum oxide, a welsbach material. It is extremely common as a byproduct of coal burning; it is commonly and openly transported. The particle size is 10 to 100 microns, consistent with the Hughes Patent. PDF of presentation: https://www.metabunk.org/sk/Chemtrails_are_Coal_Ash.pdf Some problems with this idea: He claims the percentage of aluminum oxide is about 30%. Wikipedia puts it at 5 to 35%. http://en.wikipedia.org/wiki/Fly_ash This would leave a lot of extraneous material to process out ahead of time or carry as dead weight. The percentage of al2o3 in fly ash is not that much higher than in the earth's crust to begin with. Rocks on Mount Shasta contain about 15% al2o3. The main ingredient in fly ash is silicon dioxide, which is normally in the form of sand. This would probably fall out of the atmosphere almost immediately. The narrator recommends using using this material in the form of a water slurry. However, fly ash is used as a substitute for Portland Cement. It is a binder. (Wikipedia uses the word Pozzolanic). It would quickly coagulate and fall to earth. And carrying large amounts of water as a mixer would create an additional drastic reduction in the available payload of Welsbach materials.