Seems like the yield is the same as the original Galactic Civilization 4 except maybe less ways to buff it. So far I have only gotta 0.3 out of a node using 2 extra modules in my mining starbase. I don't have all the technologies yet so I don't know if you can buff it up to 0.5 like in the original. Seems like they removed a mining yield buff from the culture tree.
