Which lunar resource is often cited as a long-term prize for mining?

Helium-3 is often cited as a long-term prize for lunar mining because it is extremely rare on Earth but present in the Moon's soil, and it is floated as a potential clean fuel for future nuclear fusion reactors, which could theoretically generate abundant energy with far less radioactive waste than today's power plants. This remains a distant prospect, though, since practical, energy-positive fusion power has not yet been achieved anywhere.

Crude oil trapped beneath the lunar surface does not exist, since oil forms from ancient organic matter that requires biological processes absent on the Moon. Natural diamonds formed deep in the Moon's core are also not an established lunar resource being pursued by mining startups.

Nearer-term interest in lunar resources actually centers on water ice found in permanently shadowed craters, since it could be split into breathable oxygen and rocket propellant, making it far more immediately useful for supporting astronauts than speculative helium-3 fusion fuel.