Rhenium is one of the rarest elements in Earth’s continental crust, with an estimated average abundance of less than 1 part per billion. It doesn’t form rich ore deposits of its own. Instead, it hides inside other minerals, concentrates in specific geological settings, and reaches commercial supply almost entirely as a byproduct of copper and molybdenum mining.
Inside Molybdenite: The Primary Source
Nearly all of the world’s rhenium comes from a single mineral: molybdenite, a molybdenum sulfide commonly found in porphyry copper-molybdenum deposits. Rhenium substitutes for molybdenum within the crystal structure of this mineral because the two elements share similar chemical properties. Concentrations vary enormously from deposit to deposit, ranging from a few parts per million to several weight percent. The highest reported concentration in molybdenite from a porphyry deposit was 4.21%, found at the Kirki deposit in Thrace, Greece. Most commercial molybdenite concentrates contain far less, typically between 6 and 460 ppm.
This matters because rhenium is never the target of a mining operation. Miners dig for copper and molybdenum. When the molybdenite concentrate is roasted to produce molybdenum oxide, rhenium oxides vaporize at roasting temperatures and escape into the flue gases. Recovery systems capture these gases through wet scrubbing, pulling rhenium out of what would otherwise be industrial exhaust. Without this step, the rhenium simply disperses into the atmosphere.
Where It’s Mined Today
Global rhenium production in 2024 was dominated by five countries, all of which extract it as a copper-molybdenum byproduct. Chile leads by a wide margin, producing an estimated 29,000 kilograms. The United States follows at 9,500 kg, Poland at 9,400 kg, China at 5,300 kg, and Uzbekistan at 5,000 kg.
Chile’s dominance stems from its massive porphyry copper deposits, particularly in the Atacama Desert region, where molybdenite happens to carry relatively high rhenium concentrations. In the United States, rhenium is recovered from porphyry copper-molybdenum mines in Arizona, Montana, New Mexico, and Utah. As of recent reporting, the Sierrita facility in Arizona operated by Freeport-McMoRan was the only domestic molybdenite roasting plant equipped to capture rhenium from flue gases. Poland’s production comes primarily from its copper smelting operations in the Legnica-Głogów region.
Its Only Known Mineral
Rhenium has exactly one mineral where it’s the primary component: rheniite, with the chemical formula ReS₂. This mineral forms as a sublimate in high-temperature volcanic vents and in certain types of hydrothermal ore systems. It was first identified at the Kudryavy volcano on the Kurile Islands in Russia, where volcanic gases deposit thin crystals of rheniite directly from the vapor. It has also been found in hydrothermal prospects in northeastern Greece, at sites called Pagoni Rachi and Konos.
Rheniite is a scientific curiosity, not a commercial source. The quantities are far too small and the locations too remote or inaccessible for mining. Its main significance is confirming that rhenium can, under the right volcanic conditions, concentrate enough to form its own distinct mineral phase.
In Seawater and Sedimentary Rocks
Rhenium also shows up in trace amounts dissolved in seawater and concentrated in certain sedimentary rocks. It behaves as a redox-sensitive element, meaning its solubility changes depending on how much oxygen is present in the water. In oxygen-rich surface waters, rhenium stays dissolved. In oxygen-depleted deep waters, it drops out of solution and accumulates in the sediment below.
Research in the Black Sea illustrates this pattern clearly. Surface waters there are enriched in rhenium, partly because rivers draining into the northern Black Sea carry rhenium concentrations up to 80 times higher than other major world rivers. But in the deep, oxygen-free layers of the Black Sea, rhenium is stripped from the water and locked into the sediment. This same process, operating over millions of years, explains why organic-rich black shales can contain measurable rhenium. These shales are not currently mined for rhenium, but they represent a significant natural reservoir of the element in Earth’s geological record.
In Meteorites
Beyond Earth, rhenium appears in measurable quantities in meteorites, particularly iron meteorites. Concentrations in iron meteorites range from 1.4 to 4,800 parts per billion, with the higher end vastly exceeding what’s found in Earth’s crust. This makes sense: rhenium is a siderophile element, meaning it has a strong chemical affinity for iron. During the formation of planetary bodies, rhenium preferentially sank into metallic cores along with iron and nickel. Earth’s rhenium is largely locked in its core, which is why so little remains in the crust for us to access.
Recycled Supply
About 10% of the world’s rhenium supply comes not from the ground but from recycling. Total annual production sits around 75 metric tons, and roughly 8 tons of that is recovered from secondary sources. The main recycled material is spent superalloy scrap, particularly turbine blades from jet engines and power plants. These nickel-based superalloys contain rhenium to improve their heat resistance, and when the blades wear out, the rhenium can be chemically separated and reprocessed. Recovery happens alongside the reclamation of cobalt and nickel from the same scrap, making the economics more favorable than targeting rhenium alone.
Given that rhenium costs thousands of dollars per kilogram and global reserves are limited, recycling is becoming an increasingly important piece of the supply picture, even if it still represents a relatively small fraction of total production.