Colony Frigates and scout ships, while great at their main jobs, are also useful for capturing random crystal and metal asteroids. Many systems will have “planets” that consist of nothing more than a few crystal or metal asteroids. You can neither colonize the area, nor you build in it, but you can capture their resources with a colony ship (use TEC or Advent), and with a Scout vessel (use the Vasari).
This answers my own question.
Found on this link:
http://www.mycheats.com/view/section/3154358/20378/sins_of_a_solar_empire/pc
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