Rare earths: Extraction

Seventeen twins that are hard to tell apart

Rare earths are 17 metals with near-identical chemistry that occur together. Light rare earths come mainly from bastnaesite and monazite in hard-rock or mineral-sand deposits. Heavy rare earths come largely from ion-adsorption clays, historically in southern China (Humphreys, pdf p. 91). At Mountain Pass, California, roughly 8 to 10% of the rock is rare earths, upgraded by froth flotation (Scheyder, pdf p. 111). The hard step is separation, which pulls the elements apart in a set order through many solvent-extraction stages. Much Chinese output comes as a companion of iron ore at Bayan Obo, and companionality is about 90%.

Rare earths come from three kinds of ore. Hard-rock carbonatites hold bastnaesite or monazite at a few per cent REO and supply most light rare earths (lanthanum to neodymium). Heavy-mineral beach sands yield monazite as a by-product of titanium and zircon mining. Ion-adsorption clays in south China and Myanmar are very low grade but rich in the heavy rare earths dysprosium and terbium, and are leached in place. Whatever the ore, the expensive and concentrated step is chemical separation into individual oxides, then reduction to metal for magnets. Mining is moderately concentrated in China; separation and magnet-making far more so.

Methods compared

How each method works

Ore is blasted, crushed and floated to a bastnaesite or monazite concentrate. The concentrate is cracked with acid, the rare earths dissolved and then separated in long solvent-extraction circuits. Bayan Obo in Inner Mongolia mines rare earths alongside iron ore, which lowers cost; Mountain Pass (US) and Mount Weld (Australia) are primary rare-earth mines.

Large, long-life deposits; but radioactive residues and complex chemistry make plants costly and slow to permit.

Rare earths are loosely held on clay surfaces. Leach solutions of ammonium sulphate or magnesium salts are pumped into the hillside or heaped clay and the rare earths precipitated from the liquor. No crushing or acid cracking is needed, so it is cheap, but leakage of leach solution has caused serious pollution in south China and Myanmar.

Main source of heavy rare earths at low capital cost; environmental damage and dependence on Myanmar's conflict zones.

Coastal sands are dredged or dry-mined and separated by gravity, magnetic and electrostatic methods into ilmenite, rutile, zircon, garnet and monazite. Monazite is then cracked with caustic soda, giving rare-earth chloride and thorium. India's IREL works this route at Chavara, Manavalakurichi and OSCOM.

Rare earths ride on titanium mining economics; thorium makes handling and licensing harder.

Mixed rare-earth chloride or carbonate passes through hundreds of solvent-extraction stages to individual oxides, which are reduced to metal by molten-salt electrolysis, alloyed and sintered into magnets. This stage needs chemical know-how, reagent supply and waste handling, which is why China retained it even as mining spread.

Captures most of the value; slow to build, and non-Chinese plants have run below nameplate (Lynas Kalgoorlie in FY2025).

By-product supply

Companionality is about 90%: most Chinese rare earths come out with iron ore at Bayan Obo, and monazite output follows titanium sand mining. Within the rare earths themselves, supply is joint: you cannot mine neodymium without also getting cerium and lanthanum. Producers sell the oxides that pay (NdPr, dysprosium, terbium) and stockpile or discount the rest, so output of any one element responds weakly to its own price.

Share produced as a by-product

Who does it: global

Who does it: India

India mines about 2,900 t REO a year (USGS 2025), under 1% of world output, through state-owned IREL because monazite carries thorium. It imports almost all its magnets, mainly from China. The 2023 MMDR amendment opened exploration to private firms, and a Rs 7,280 crore scheme (Nov 2025) funds 6,000 tpa of domestic magnet capacity.