The chain’s vocabulary

Short, plain-language definitions for the terms used across the Factbook. For how facts are verified, see the methodology.

Rare earth elements (REE)

Seventeen metallic elements (the lanthanides plus scandium and yttrium) whose magnetic and optical properties make them essential to motors, electronics, and defense systems.

NdPr (didymium)

Neodymium and praseodymium, mined and separated together; the main input to NdFeB magnets. Traded as NdPr oxide and NdPr metal.

NdFeB

Neodymium-iron-boron, the strongest class of permanent magnet; made from NdPr with heavy rare earth additives for high-temperature performance.

Heavy rare earths (Dy, Tb)

Dysprosium and terbium, scarcer elements added to NdFeB magnets so they keep working at high temperatures — the chain’s tightest supply constraint.

Bastnaesite / monazite

The two principal rare earth ore minerals. Bastnaesite is mined at Mountain Pass, California; monazite is recovered largely from heavy-mineral sands.

REO / REO-equivalent

Rare earth oxide. Production and capacity figures are often stated as the equivalent weight of oxides to make different materials comparable.

Mixed rare earth carbonate (MREC)

An intermediate compound produced by cracking and leaching concentrate; the typical feed for a separation plant.

Separation

Splitting mixed rare earths into individual oxides, usually by solvent extraction — historically concentrated in China.

Metallization

Reducing oxides to metal, the step between separation and magnet alloy. U.S. commercial NdPr metal production resumed in 2025.

Offtake

A commitment to buy a facility’s future output; governments use offtakes to guarantee demand for new plants.

Price floor

A guaranteed minimum price. The 2025 MP Materials–DoD agreement set a $110/kg floor for NdPr.

DPA Title III

Defense Production Act Title III — the Pentagon’s main authority for funding domestic industrial capacity, used for rare earths since 2019.

IBAS

Industrial Base Analysis and Sustainment — the DoD program that funded the heavy rare earth separation contracts.

OSC

The Office of Strategic Capital, DoD’s credit office; its loans are conditional commitments until disbursement conditions are met.

DLA

Defense Logistics Agency, manager of the National Defense Stockpile; buys magnets and strategic materials.

DFARS magnet rule

The defense acquisition rule (10 U.S.C. 4872) barring Chinese-origin magnet content in defense systems, tightening to mined-and-refined content in 2027.

FOA / NOFO

Funding Opportunity Announcement / Notice of Funding Opportunity — how DOE and other agencies solicit applications for grants.

NOI

Notice of intent — an agency’s announcement that a funding opportunity is coming before it formally opens.

BAA

Broad Agency Announcement — a standing solicitation for proposals, like DLA’s strategic materials BAA.

RPP / OTA

Request for Project Proposals under Other Transaction authority — how DoD consortia like DIBC award projects outside standard contracts.

EUL

Enhanced Use Lease — the Army’s authority to lease installation land to companies, used for critical mineral processing in 2026.

Qualification

Proof that a product meets a customer’s specification. An operating plant is not the same as one producing qualified output.

Nameplate vs. demonstrated vs. target

Capacity figures differ: nameplate is designed capacity, demonstrated is achieved output, target is an announced goal not yet built or reached.

Mine-to-magnet

Shorthand for a complete domestic chain: mining, separation, metallization, alloy, and magnet manufacturing.