photo #1577416

It's called thermite.

May have been mixed into materials and sprayed onto beams as a sound buffer while under construction. Construction crews probably had not a clue, if it was in fact contaminated materials. Well planned

Let me add to the issue. traces of thermite was found in the ash. Why was it there at all? ? Yes! Blacksmiths used a bellows to direct flame to a concentrated spot on steel. Think of a cutting torch. Simply blowing air across flame does nothing.