How fast Mining will works will be the Key factor in the game to how easy and fast Player can Build constructs and fight in PvP Fights.
Its impotent that Resources are not completely worthless but at the same time not way to expensiv, that is an very impotent factor on how the game will play.
I think the mining it self should go pretty fast so that the main cost of Resources will be the transportation and the Risk of transporting the Minerals and not the Minerals it self.
So The main cost of Resources should be decided by the flowing factors: Risk for Mining, Risk of Transport, Defense of Transport, Finding Minerals, Claiming/Finding the Areas for Mining
And not the time you need to Mine the Minerals, that would be boring farming that no one or most people do not want to do.
What would be a Healthy for the Gameplay experience from my point of view.
1. Not every Resource should be found in masses on all planets, every planet should have a Resources the have way to much and such they have way to less.
2. Mining times should not be a problem, this gets annoying very fast. The problem on mining should be Finding the Resources not The process of Mining them.
3. Resources should be Cheap as possible not to cheap but so cheap that people don't risk a Lot of time/Money by Fighting in PVP.