Cobalt Ore is one of raw ores available from mining asteroids. It can be found on planets and moons, occurring as nodes underneath the surface. It can be processed in a Refinery or an Arc Furnace to produce Cobalt Ingots.
Cobalt Ore may also be found aboard Cargo Ships.
Ore distribution is based upon a random seed for the map. Some ore will be plentiful and you’ll find them on many asteroids. Some ore will be less plentiful and you’ll only find them on a few asteroids. And some ore will be rare. One ore will be extremely rare. If this ore is nickel then your game will be almost impossible. But with cobalt it is not insurmountable.
Once you have searched a few asteroids in a local area (about a 10km area) and not found any there will probably be none on any other asteroid in that region due to the way the ore is spawned. You’ll need to move a minimum of 50km or even 100km and start you search again. This will cause the game to spawn additional asteroids and this process usually results in the game spawning some with the ore that has not previously been spawned.
So just pick a random direction and go a minimum of 50km and start searching again.
Ores except platinum are either in those rocks laying about or below those darker patches. Keep in mind the range limitation of handdrill vs. small detector vs. large detector when searching.