Asteroids
From Chosen Space V2 Wiki
Asteroids are massive pieces of rock which float through the systems of the galaxy.
There are a handful of smaller asteroids in each inhabited Star System,
and a single massive asteroid in each uninhabited Expanse.
Asteroids are harvested (by mining ships) for the valuable ores they contain.
The various ores can be taken to Refineries to be turned into much more profitable finished metals.