Pharmaceutical Isolators, oh dear they are for sure bugged.
Selenium can't find that anywhere either.
The good old working as intended hangs over as always despite years yeh YEARS of non spawning mats...
As been nicely explained by
@Red Anders things are a bit more complicated than they appear.
Pharma Isolators, Improvised components and Military Supercapactors are the rarest of the rare.
So to increase your chance to find Pharma Isolators, for example, you need to check Inara for:
- systems with factions in outbreak (searching the galmap for systems in outbreak will have a much lower chance to get any PI, really low actually)
- then check those systems to make sure the faction in outbreak does not have any other states (it will greatly decrease the chance to generate HGE with PI)
- then make sure there are no other factions with states generating high quantity of HGE (especially Boom, Investment, Expansion) - unless you want to go the trade route
- then make sure it's a single star system or a close multi-star-system, else you might have to travel 50,000-100,000 or ever more LS, and you might miss them or worse
- make sure it's an Alliance/Independent system - else it will have the chance to spawn Core Dynamics or Imperial shielding (less chances, but still) instead of PI
- and dont forget they are really rare. So even with all above, you might still not get any...
For Selenium, again an
external tool is the savior. It will list the planets with the right combination of materials for a greatly increased chance to find Selenium
And why is Selenium rare?
Because it's treated as a tier2 (G2) material instead of a pure Tier4 (G4) and so it has no Crystalline Shards and it pops in bio/geo sites rather differently then the rest of G4 materials.
Each geo/bio site will have a list of spawns composed of 1x G4, 2xG3, 3x G2 and (most od the time) all G1materials. Also a specific number of spawns with G2 materials.
IF the Selenium percentage is equally to the other 2 materials from the same tier, then most probably from 6 spawns you will get 2 selenium (actually 6 since each collected piece is worth 3 materials)
What the site mentioned above does, is to select the planetary bodies with a higher percentage of selenium than the other 2 G2 materials, so you'll get more selenium than the other 2 G2 materials.
So lets look at the system below:
Se Share means that Selenium holds almost 66% of the combined G2 materials. So out of 6 G2 spawns, you will have a chance to get 4x Selenium, 1 Arsenic, 1 Zirconiiu
So it's a damn good planet, not only because it has lots of Selenium, but because you can get Arsenium aaaand Tin which is the G3 material in the same line with Selenium
The bad about the above system? really low gravity and geysers... so you will chase those fly high materials a lot... and dont even try to see what a geyser might do to your srv (hint: i can see my house from here...)
But they aren't rare.
You know what's rare? Some of the G1 mats. Some of the G1 mats barely spawn at all.
Different G1 materials spawn in different places from different ship types (if we talk about Manufactured). SO if you stay only in a CNB, you'll miss some types of materials.
Lucky enough, traders have decent rates when you trade down.