fulminate of mercury

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A gray crystalline powder, HgC₂N₂O₂, that when dry explodes under percussion or heat and is used in detonators and as a high explosive.

GNU Webster's 1913

1. n. (Chem.) The mercury salt of fulminic acid (Hg(CNO)2), called also mercury fulminate. It is prepared as gray crystals, and is used primarily in detonators for detonating high explosives, such as dynamite or TNT.

WordNet 3.0

1. n. a fulminate that when dry explodes violently if struck or heated; used in detonators and blasting caps and percussion caps