One of the more annoying things about the current setup is that resources located in-system to a habitable planet are very rarely exploitable, in a practical sense.
Given that Administration is a precious ability, it's not really worth creating a mining starbase for just a single resource, unless you have no other options to get that resource. Which means, on maps where you have a fair amount of planets, placing mining starbases next to habitable planets is a waste of Administration. You really only place starbases where they can mine multiple resources and/or artifacts. Lone resources are really not useful, and can't be justified against the cost of an Administration point.
It also means that the location of the resource is wasted, since it takes up what would otherwise be a usable asteroid mine.
We've also lost the ability (a long time ago, IIRC) to place mining AND economic rings on the same starbase.
So the end result is that, for even mid-sized maps, there tend to be a lot of singleton resources unexploited. And, of course, the AI has a bad tendency to want to claim these resources, even if they're deep in someone else's territory, which leads to all sorts of perverse stuff.
Given that I don't see having mining and economic rings co-existing again, I'd like to suggest a solution to this annoyance: planet-based mining facilities that enable resources (not artifacts, just resources) to be mined.
My view is that they should be less efficient than mining starbases, and have a fixed, non-expandable radius. Just enough to grab resources in-system, and not 10 or 20 hexes away.
As such, I'd like to propose 2 new Improvements, available to all races:
Mining Facility: available on the Interstellar Mining technology. Costs 100 production to make, and 1 Durantium. Maintenance of 1. Allows collection of resources at a rate of 0.10/turn. Is of a All Production type, provides a +1 All Production adjacency, and receives a +2.5%/level All Production bonus.
Mining Center: available on the Resource Extraction technology. Upgrade from Mining Facility. Costs 250 production to make, and 2 Durantium plus 1 Promethion. Maintenance of 1. Allows collection of resources at a rate of 0.20/turn. Is of a All Production type, provides a +1 All Production adjacency, and receives a +5%/level All Production bonus.
Both would be One Per Planet, with a max distance to resource of 4.
Would this be possible solely via a XML change, or would the "EffectType = Mining" have to be coded in for Improvements, not just StarBases?