[Born to Conserve]

I had an O chem professor that loved to pour metal powders out of test tubes, the cloud of dust would spontaneously explode into flame and disappear before it hit the ground. Copper precipitate was particularly awesome.

[Ichneumon]

I had an O chem professor that loved to pour metal powders out of test tubes, the cloud of dust would spontaneously explode into flame and disappear before it hit the ground. Copper precipitate was particularly awesome.

That works with a lot of powders: Flaming non-dairy creamer.

And the same principle is at work in grain-elevator explosions.