Might be Hg fulminate. For sure metallic Hg won’t explode, though in the USA it can cause terror. Not to far away from where I live, a school got shut down for several days because of a mercury barometer.
The post text is pretty unintelligible, no telling what was actually meant.
Mercury is a liquid metal and turns into thousands of little balls that act like shrapnel.
The suicide vest has an inner layer of common explosive with an outer layer of CF bulbs.