The Anti Matter Mines of Star Trek: Armada are inspired by the mines used in the Star Trek: Deep Space Nine show and are very similar to those. They also are laid by Defiant class ships and approach nearby enemy ships. The main difference to the show is, that they are not cloaked at all. In-game this means, once you use the special weapon, a mine is ejected from the ship. If an opponent's ship is nearby or getting to close, the mine will begin acquiring a target. If there are more than one to choose from, the selection is random. (It is not necessarily the closest one.) Once impacting on the ship, it will deal some damage to it. It is researched at the Research Facility. This looks as shown here:

Anti-Matter Mines will also target cloaked ships, making them decloak on impact.

If a targeted ship manages to outrun the mine, the mine will vanish on its own after a while. So casting them a lot to lay a mine field does usually not pay off, as the mines do not stay long enough. In combat on the other hand they can be quite useful. An active Corbomite Reflector has no effect on this special weapon. The Shield Remodulation and Phase Cloak on the other hand, do protect from it.

The Anti-Matter Mines are also used by the campaign ship Avenger. The 5000 special energy will give it the means to use Anti-Matter Mines up to 10 times in a row.