Laser Mining Selenium (I tried this myself and filled selenium completely up, but it still took me some time):
Delkar 7, B Ring (rocky) drops Selnium when asteroids are mined (material content medium and high, in low I found none). It has a res, but I did find less Se there. Ignore the materials from the fragments or the cargo once processed and ejected (they are junk anyway) to prevent limpets from wasting time collecting them and keep pirates from jumping on you.
Strangepork: "Res sites also prompt larger yields. Pristine/Haz Res being the most bountifull.
Here is the trick DONíT fit a refinery. The limpets then focus solely on mats you arenít full of. The pirates leave you alone because you have nothing in the hold.
Very rare mats also drop surprisingly often.
Each ring type in differing locations drop different ranges and types of mat."
You can collect it in an SRV or small ship from surfaces, in that case only from geological sites and only from Crystalline Clusters as I understand.
"Wolf 587 4ea has the highest incidence of Selenium in the bubble, and something like 25 Geo' POIs where you can collect it from the mid-tier drops, which means each site can yield a dozen or so drops. Alternatively, if you're in Colonia, head for Eol Prou NH-K C9-10 A4a/A4b."
Getting Selenium:
- Planets with Brains Trees
- Planets with Geological Sites / without them, high selenium (>= 3.1%?) and good % ratio selenium vs. materials of the same drop category on the planet (Common, arsenic or vanadium plus zirconium). https://edtools.cc/selenium?s=sol
LTT 5212 ABC 5 b (Se=4.5%) (0.04 G) (ShinDez < 17.51 ly) Tiny, low gravity, but outcrops spawn really close to each other.
geo sites of LHS 417 9 E A. 4.9% Se and in total 2.5% of As and Zr means 2 out of 3 drops from crystalline fragments are selenium
HIP 83204 3 b A even better, Geological Signal (16). 5.01% Se vs 2.22% Zn+As 0.05G 38.23ly from sol, 1.93kls from star. Low grav but not too low , very nice to navigate, boosting and going high speed no problem, almost no annoying rocks or bumps that screw around with your SRV. Absolutely unobstructed landing possible with large ships without even having to bother to look for a proper spot.
Wolf 587 4EA, Not especially prevalent, but a quick visit to the Geo POIs will get you enough for a G5 mod.
prthi 2a Mesosiderites have 80% Se, other rocks 50%.
"Don't forget too that you can just collect surface mats from volcanic sites very easily in a Sidewinder, without SRV.
Just fly down, eyeball the nodes, shoot em off with a pulse laser and scoop em up.
You can strip a field a hell of a lot faster in a ship than an SRV, and it's fun
"
"I use mines, blanket the area from high above, then quickly land, watch the fireworks show (the mines fall like snow, very slowly), then scoop. The problem with both of these methods though is you have to be super fast to get all the mats before they despawn. I usually just drop one batch of mines on a small area, then shoot the rest after landing. The worst case is you get loads of really good hits, and hardly have time to collect anything before all the materials despawn and you cleared the field for yourself for nothing!
Blanketing an area with frag fire works too, but same problem."
"If ever you are at the bug killer site, try its neighbor 1b , it is loaded with lots of selenium. and more. on average, an hour there easily gets 100+
if you were not aware, bug killer has 3 cargo racks and 3 data points and thargoids to watch."
Every planet has 5 materials from the G1 pool in Piceous Cobble, 3 materials from the G2 pool (strangely including selenium) in Crystalline Fragments / Mesosiderides, 2 materials from the G3 pool in Crystalline Clusters and one material from the G4 pool in Needle Crystals.
The mesosiderite scan wave is the small one in the bottom of the wave scanner with a single line through it.