Tungsten Ore

Tungsten Ore can be found on most tier 2-2.4 planets, including the Desert and Forest planets in the starting system.

It exists in great quantities on Mountainous planets.

If needed, it can be obtained even on the first Garden planet (either from Iron Ore or by centrifuging Lava). Note that this planet is tier 1 and doesn't have any Tungsten Ore in the ground.