In my tech college metal shop, there was an old all-round coarse grit pedestal grinder, up to a certain point.
Pretty neglected, probably never cleaned, so grinding dust built up in and around it,
until it one day set itself ablaze. The fire burned tru the covers, melted itself thru its pedestal top plate etc.

Analysis was: all ferrous grinding dust rusted in the pretty moist conditions in there, and quite a few did aluminium grinding there also.
Providence saw to it, that the Fe2O3-Al mix reached the necessary proportions for a Thermite fire.
I wasn't there when it happened, but it certainly got me interested in the Artistic possibilities of Thermite /Electron (Mg) incendiaries.