Procellarum KREEP Terrane (PKT) on lunar near side, especially Oceanus Procellarum and Mare Imbrium ejecta
Acronym for Potassium (K), Rare-Earth Elements, Phosphorus — geochemically anomalous material concentrated in the last lunar magma ocean fraction to crystallize. Source of lunar thorium + uranium signatures detectable from orbit. Of long-term interest for in-situ fission fuel + plant-growth nutrient potassium/phosphorus, not for Earth export.
Lunar REE enrichment is *relative* to other lunar regions — absolute concentrations are still parts-per-million scale and lower than terrestrial REE ores. China and Australia produce REEs at $10-100/kg ranges; even speculative lunar prices are $1,000+/kg delivered to Earth. Economic viability requires either: (a) in-space utilization (no transit cost), or (b) a global REE export ban from Earth producers. Neither is imminent.