Fulminated mercury has the molecular formula Hg(CNO)2. It is a white power that explodes with the formation of mercury vapors in response to impact, friction, or heat.
Does fulminated mercury really explode?
Fulminated mercury [Hg(CNO)2] is indeed an explosive, classically used as a trigger in blasting caps used to set off larger explosives.
What does Walter White throw that exploded?
The bag of meth crystals he has just given Tuco were in fact "fulminate of mercury". He throws a crystal on the ground which detonates, creating an almighty explosion. We see Walt walking victoriously from the smoking remains, clutching his bag of money.
