How to Find Lithium
There’s tons in the cave systems on enforcement island.
That’s the island to the north with the big mountain and the alien base. If you look from the ocean surface, the island is covered in clouds until you get close to it.
But also mushroom forests and jellyshroom area, you can sometimes just see it lying around.
Jellyshroom caves are below the safe shallows where you first crash land.
Pay particular attention to the shafts of mushroom trees, and the vertical faces of cliffs and escarpments, and the interior walls of caves. Lithium nodes are nondescript. Shale Outcrops yield Lithium ~1/3 of the time. Search the interior of the above water caves of the Mountain Island when/if you get there.
It is a process. Lithium does not occur in clusters.
And…build a Scanner Room, as soon as you can. Be prepared to build another, or move it around. Lithium is NOT the most difficult to recognize mineral you will have to find.
I think a general rule is that if you find one, then set up a small base with a scanner room nearby and find more with it. For every one you can find by just looking there are many more that you miss because they’re hidden in a bush, under something, or just plain camouflaged against the background. You can always deconstruct the base to recycle the materials if you’re worried about that. That goes for any resource that appears in the scanner room, not just lithium.