Antimatter charge
From Halopedia, the Halo wiki
The Antimatter Charge is an explosive weapon used by the Covenant[1]
They use antimatter charges in a variety of ways. To blow through ship armor during boarding action, or as anti-vehicle and anti-personnel weapons. These appear to be the choice explosive of Ranger Elite teams, as they have sometimes been used to destroy Magnetic Accelerator Cannons on board ships.
Antimatter is extremely unstable; any contact between unstable anti-matter and normal matter causes an instant, massive explosion of energy, annihilating any and all matter within the radius.
Only one kilo of antimatter reacting with one kilo of matter would yield an explosion of 42,96 Megaton, which almost is equivalent to three Hiroshima-bombs (45 Mt combined). Antimatter-matter is the most pure and most efficient way of producing energy, e=mc². E being energy equals mass times the speed of light squared.
