Where the Tellurium Hides: A Global Database of Critical Minerals in Ores

Nearly 90% of the world's tellurium — used in steelmaking and solar cells — comes from porphyry copper-molybdenum-gold deposits, mines dug for copper and molybdenum. That is the pattern for many critical minerals, the commodities modern industrial and strategic technology depends on and whose supply is highly vulnerable to disruption: they are produced in small but essential quantities alongside a primary metal such as copper or zinc. Because nobody mines for them directly, public data on how much of them an ore holds is sparse.

The Critical Minerals in Ores (CMiO) database is built to fill that gap. It comes from the Critical Minerals Mapping Initiative (CMMI), a collaboration of the U.S. Geological Survey, the Geological Survey of Canada and Geoscience Australia to understand where critical minerals are found worldwide.

What is in it

Where the database's samples come from, coloured by deposit environment. Future updates could fill gaps for particular environments, groups and types; an interactive map is at portal.ga.gov.au/persona/cmmi. USGS.

Abundances of select critical minerals in each deposit environment, on a log scale relative to each element's abundance in Earth's crust. USGS.

What the minerals are for

Two examples

Copper mines as a byproduct source. Porphyry copper-molybdenum-gold deposits, part of the porphyry group in the magmatic hydrothermal environment, are a major global source of copper and molybdenum and could also yield selenium, rhenium and platinum group elements as byproducts. Samples from U.S. deposits show how much those concentrations vary from deposit to deposit — the comparison an assessment of byproduct potential needs.

Selenium, tellurium and rhenium in mineralized samples from U.S. porphyry copper-molybdenum-gold deposits; dashed lines mark average crustal abundance. USGS.

Settling a classification. How iron-oxide-copper-gold (IOCG) and iron-oxide-apatite (IOA) deposits form is still hotly debated. The database groups them in the regional metasomatic environment and splits IOCG deposits into hematite-dominant and magnetite-dominant types. The data seem to confirm the split: magnetite-dominant IOCG deposits are more likely to be enriched in cobalt, while light and heavy rare earths are more enriched in IOA and hematite-dominant IOCG deposits.

Cobalt, copper, scandium, lanthanum and dysprosium in IOCG and IOA deposits worldwide, with each deposit's ore tonnage. USGS.

Adding data

The CMMI is asking academia, government and industry for high-quality geochemical data from ore deposits, to widen the database's geographic reach and the deposit types it covers. Samples should be well characterized geologically and analysed by modern methods; the submission guide and data template are at doi.org/10.26186/149408.

Sources

Based on "Critical Minerals in Ores (CMiO) Database: A Global Geochemical Database to Assess Primary and Byproduct Critical Mineral Potential," U.S. Geological Survey Fact Sheet 2025–3002, drawing on Kelley (2020), Emsbo and others (2021), Champion and others (2021), Hofstra and others (2021) and Wedepohl (1995); a work of the United States government in the public domain.