Mercury fulminate

Mercury fulminate, Hg(ONC)₂, is an explosive that is highly sensitive to shock, and used to initiate processes leading to the detonation of a high explosive or a explosive-based propellant. While it is powerful and relatively easy to prepare, it has been replaced, in manufactured ammunition and explosives, principally by lead azide preparations.

It is a salt of fulminic or paracyanic acid, which polymerizes very rapidly in both aqueous and ethereal solutions, and so cannot be isolated. The structure of fulminic acid, and thus the salts of this acid, is undetermined. Anhydrous mercury fulminate has a molecular weight of 284.65, or, as the hydrate, 293.64.