Hey there, resource nodes are things like 'Dusklight Shards' in the EDZ, they look like blue crystals. Another example is 'Spinmetal Leaves', they look like a metallic leafy plant, sprouting from red barrels, those are found on the Cosmodrome. In The Pale Heart, the resource node is called 'Stigma of the Witness', it looks a bit like a cactus with an orange glow. They appear randomly around the map, like chests. You can put a mod on your Ghost to highlight nearby resource nodes, which might help you track them down, they will show up as a little pyramid icon.