These are the only places on the map where Mass extractors can be built. The mass deposit is critical to the start of every player's economy. Controlling as much mass deposits as possible while denying their opponents' access to them is a core aspect of most skirmish games.
In vanilla SupCom, the Mass fabricator, which does not have to be built on a mass deposit, takes over in the form of massive power grids adjacent to power generators, capable of generating hundreds of mass points with no real energy setback. However, in Forged Alliance, the Mass Fabricator has been limited, requiring much more energy, for less mass, to promote expansion, and reduce the effectiveness of Turtling