Until recently I was blissfully unaware of the possibility of something called Thermite Sparking. It is a variety of the classic Thermite reaction, only it can happen inadvertantly in the workplace by mechanical friction. 

Thermite sparking is a circumstance wherein an aluminum part smartly strikes an oxidized iron component generating a momentary and highly localized spot of molten metal. Normally, the thermite reaction is limited to the small mass of material in the impact zone and does not progress further.

What is is useful to know is that aluminum and iron together constitute a sparking pair of materials and could serve as an ignition souce for flammable liquids and vapor in the area. An aluminum cart or pallet could suffer an impact while in motion and provide an ignition source for a fire.