An Asteroid is a type of environment that provides 1 
Raw Production (before decay) to the nearest colony upon construction of a mining base, which costs 100 
Treasury and takes three turns to build. 
Durantium is also found on asteroids.
Raw Production decay
The Raw Production provided by a mining base to a colony starts to decay 0.025 Raw Production per tile after a distance of 6 tiles, down to a minimum of 0.1 Raw Production.
Combat
When attacked, a mining base has 10 
Hit Points and 1 
Missile Attack.