That makes sense!  I removed black holes completely, I hate them, but thats why I have No anti-matter whatsoever each game

Great Job with your tests!

No actually, I really only looked at the 3 for weapons. Thanks for the info on Thulium, that makes sense! I think Promethium must be some other combo with the ResFreq stat, dunno which yet. I'll keep an eye out in future games to see where it mostly appears.

Promethium comes from gas giant dead worlds if that's any help. Thulium is also from dead worlds and I am not aware of any special quality that further differentiates it from the other dead worlds.

I have not noticed any shortage of Thulium on the largers maps I have been playing but Promethium is definitely in short supply compared to all but the anti-matter which is next to non-existent.

Editing the StarSystemDefs.xml to change the quantity of planets in the <LaneType>OuterZone</LaneType> Orbit Lane to a minimum of 1 does indeed significantly boost the amount of promethion that appears in games I changed it to min 1 max 3 and even in a tiny map I repeatedly had systems with multiple promethion.  Be aware however that the map generator has a max cap on the number of planets so this can negatively impact the appearance of thulium as very few appeared, and it might impact habitable worlds although from what I can tell those are handled separately.

I've been tweaking those numbers a lot, and it's a nightmare to figure out properly. The system group in StarSystemsDefs.xml decides how many of which planets spawn, but it's random how many of each system you get, so you will get wildly different numbers even without touching the resource settings. The main issue is you want *some* Thulium and Prometheon, but not too much of it, and it's very easy to get way too much. 

Then, you have map sizes and their base number and you may want completely different values making finding a 'right' setting impossible. If you just want more of both I suggest going to the abovementioned xml file, and just up the number of planets in 'asteroid' and 'outerzone' lanes for more Prometheon, and 'deadzone' for thulium. (SystemGroup at the bottom of the file) If that does not do the trick, edit MapSizeDefs.xml and up the base number of the map size you are playing. (this will give you tons more of the other resources as well though)

<MinablePlanetChance>1.5</MinablePlanetChance>

I haven't touched this one though, you might be able to fix it purely by tweaking that number and the planet spawn rate a bit. I've mostly tried to get the number of habitable planets right for my mapgenmod, Prometheon and Thulium generation has been a secondary thing to test.