The oil pump and geo miner can extract resources from a chunk after it is scanned by a gps, but these resources are nonrenewable. Each chunk has a fixed, random amount these resources, and when it's out, no more can ever be extracted.
The Oil Pump can extract Oil and the Geo Miner can extract Nether Ice, Uranium, and Salt.
I believe of the four resources above, the only ones that are completely impossible to obtain in any way other than by extracting from chunks is Oil and Nether ice, so there should be a way of getting more of it without exploring new chunks because you simply can't do that on a skyblock island.
