fulminate of mercury

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A gray crystalline powder, Hg(CNO)₂, that when dry explodes under percussion or heat and is used in detonators and as a high explosive.

from the GNU version of the Collaborative International Dictionary of English.

• noun (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.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a fulminate that when dry explodes violently if struck or heated; used in detonators and blasting caps and percussion caps