Stockpiling and Inventory Cycles in Critical Mineral Markets
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Critical mineral inventories sit with four kinds of holder: exchange warehouses, consumers and processors, traders and investors, and governments. Only the first is public for most minerals. The clearest 2025 inventory movement in the USGS data is cobalt: after Congo (Kinshasa) banned exports in February, U.S. industry stocks rose from 956 tonnes to an estimated 1,500 tonnes, an increase of 57%, as imports rose to 14,000 tonnes. This page covers the inventories that move markets, and the strategic reserves page covers government programmes in detail.
+57%
rise in U.S. industry cobalt stocks in 2025, from 956 to 1,500 tonnes, which USGS says the Congo export ban likely contributed to
25,000 t
of nickel held by U.S. consumers at the end of 2025, against 110 tonnes in London Metal Exchange warehouses in the United States
217,000 t
of lead in LME-approved warehouses worldwide at the end of October 2025, 10% less than at yearend 2024
2023
the year from which USGS no longer publishes Government stock changes in its salient statistics
Where do critical mineral inventories sit?
The four holders differ in how much they hold, how visible the stock is and how it affects prices. The table gives 2025 examples from USGS where they exist.
| Holder | 2025 example (USGS) | Visibility | Effect on the market |
|---|---|---|---|
| Exchange warehouses | Lead: 217,000 t in LME-approved warehouses at the end of October. Nickel: 110 t in LME U.S. warehouses at yearend. Cobalt: 34 t in LME U.S. warehouses. | Public, but only for the few minerals traded on an exchange | Falling stocks signal tightness and rising stocks signal surplus; the U.S. volumes are small next to consumption. |
| Consumers and processors | Cobalt: industry stocks 1,500 t, up from 956 t. Nickel: consumer stocks 25,000 t, against 25,500 t a year earlier. Gallium: consumer stocks 3,400 kg. | Partly visible, from U.S. surveys | A buffer that is built when supply looks uncertain and run down when it is not. |
| Traders and investors | USGS says its cobalt industry stock figure excludes stocks held by trading companies and held for investment purposes. | Not published | Can absorb or release metal without appearing in any statistic. |
| Governments | A cobalt solicitation for 7,480 t was published and then cancelled; plans to buy more than 6,000 kg of scandium oxide were announced; an $8.6 million tantalum ingot order was awarded. | Partly visible, through solicitations | Adds demand outside the commercial cycle; USGS no longer shows Government stock changes. |
Source: USGS Mineral Commodity Summaries 2026 chapters on lead, nickel, cobalt, gallium, scandium and tantalum. The 2025 figures are USGS estimates for the United States unless the table says otherwise.
How do inventory cycles show up in prices and trade?
Cobalt in 2025 shows a restocking cycle. Congo (Kinshasa) banned cobalt exports in February to address oversupply and low prices, then replaced the ban in October with quotas of 18,125 tonnes for the rest of 2025 and up to 96,600 tonnes a year in 2026 and 2027, including 9,600 tonnes for its own strategic reserves. USGS says uncertainty about supply after the ban likely contributed to the sharp rise in U.S. imports and industry stocks. The U.S. spot cathode price rose from $16.77 per pound in 2024 to an estimated $21 in 2025.
The reverse also happens. USGS says the fall in the U.S. magnesium import price from $3.25 to $3.13 per pound was potentially attributable to sufficient inventory and decreased demand for primary magnesium. For rare earth yttrium, USGS notes that U.S. consumers of compounds and metals relied on imports and stockpiled inventory, which is what a buffer is for.
Why are inventories hard to measure?
Most critical minerals have no exchange and so no daily stock figure. USGS reports stocks for only some of them and warns of the gaps: its cobalt stock estimate leaves out traders and investors, and for strontium it says stock data were not available. As a result apparent consumption, which USGS defines as production plus imports minus exports adjusted for stock changes, can mix real use with stock building. The supply and demand models page shows how analysts handle that gap.
Frequently asked questions
What is a critical mineral inventory?
A critical mineral inventory is any stock of a mineral held outside production: in exchange warehouses, in consumers' and processors' stores, in trader or investor hands, or in government stockpiles. Each is measured differently and only exchange stocks are public for most minerals.
How did the Congo cobalt export ban change inventories?
USGS estimates U.S. industry cobalt stocks rose from 956 tonnes to 1,500 tonnes in 2025 and imports from 10,800 to 14,000 tonnes. It says uncertainty after the February export ban likely contributed to the increase.
Do governments buy critical minerals for stockpiles?
Yes. In 2025 the U.S. Defense Logistics Agency announced plans to buy more than 6,000 kilograms of scandium oxide over five years and awarded an $8.6 million order for tantalum ingots, but a solicitation for 7,480 tonnes of cobalt was cancelled. Congo's own 2026 and 2027 export quotas include 9,600 tonnes for its national strategic reserves.
Why do inventory data matter for prices?
Inventory changes separate real consumption from stock building. Rising consumer or exchange stocks mean supply exceeded use in that period, while falling stocks mean the reverse, so analysts read them as an early signal for prices.
Sources
Read on October 13, 2026. Figures on this page come from these documents; where a number is an estimate, the source says so.
- USGS Mineral Commodity Summaries 2026: cobalt. Salient statistics, stocks and events
- USGS Mineral Commodity Summaries 2026: nickel
- USGS Mineral Commodity Summaries 2026: lead
- USGS Mineral Commodity Summaries 2026: gallium, magnesium metal, yttrium, scandium, tantalum, strontium and zinc. Stock and stockpile passages
