fulminate (fŭlˈmĭnāt) [key], any salt of fulminic acid, HONC, a highly unstable compound known only in solution. The term is most commonly applied to the explosive mercury (II) fulminate, also called fulminate of mercury, Hg(ONC)2. The pure compound forms white cubic crystals. It is made by the action of nitric acid on mercury metal in the presence of alcohol and is often collected as a gray or brown sandy powder. It is very sensitive to heat, shock, or friction and is used in primers, detonators, and blasting caps.