RheniumEdit

Rhenium is a dense, silvery-white transition metal with symbol Re and atomic number 75. It is among the rarest elements in the Earth's crust and is almost always obtained as a byproduct of refining molybdenum ores or, to a lesser extent, copper ores. Its standout feature is an extraordinary resistance to heat and corrosion, which makes it indispensable in specialized industrial applications where extreme conditions prevail. Because it is scarce and expensive, rhenium’s use is highly selective, concentrated in aerospace, energy, and high-value chemical processing. In geochemistry, the long-lived radioisotope 187Re decays to 187Os, a fact that underpins the Re–Os dating method used for geological and planetary samples. Periodic table Transition metal Molybdenum Re-Os dating

Properties

Physical properties

Rhenium has one of the highest melting points among all elements, typically cited around 3179°C, and a boiling point near 5596°C. Its high density—about 21.0 g/cm³ at room temperature—combined with hardness and strength, enables it to retain strength at temperatures where many metals soften. These properties are characteristic of refractory metals, which are valuable in components subjected to severe thermal loads. For practical purposes, rhenium is often alloyed with other metals to maximize high-temperature performance. Melting point Density Refractory metals

Chemical properties

As a late, heavy transition metal, rhenium forms a range of oxides and intermetallic compounds. In gaseous and oxidizing environments at high temperature, it tends to form volatile oxides such as Re2O7, which reflects its chemistry under process conditions in catalysts and high-temperature alloys. Rhenium can participate in carbide and nitride formation at extreme temperatures, contributing to the resilience of Re-containing materials in demanding applications. Oxide Carbide Nitride

Isotopes and dating

Naturally occurring rhenium consists mainly of two isotopes: 185Re (stable) and 187Re (radioactive with a very long half-life, approximately 4.1×10^10 years). The 187Re decays to 187Os, and the evolving ratio between these isotopes is exploited in Re–Os geochronology to constrain the age of rocks and meteorites. This dating method has become a valuable tool in understanding planetary differentiation and crustal evolution. Isotopes Re-Os dating Geochronology

Occurrence and production

Rhenium is extremely rare in the crust and is not found in concentrated native form. It is typically produced as a byproduct during the processing of molybdenum-bearing ores, most notably molybdenite, and to a lesser extent from copper-bearing minerals. The economic viability of rhenium production hinges on the scale of molybdenum ore processing and the market demand for rhenium-containing materials. Major production regions include porphyry molybdenum ore districts and other hard rock deposits associated with pyrometallurgical and hydrometallurgical processing chains. As a byproduct commodity, supply is highly sensitive to the health of the broader mining sector and to the price signals of aerospace, refining, and chemical-processing industries. Recycling from spent catalysts and high-temperature alloys also contributes to supply stability. Molybdenum Molybdenite Copper ore Recycling Critical raw materials

Applications

The distinctive combination of high-temperature strength, creep resistance, and corrosion resistance makes rhenium valuable in a few specialized domains:

Aerospace and power generation: Rhenium is incorporated into nickel-based superalloys used for turbine blades, vanes, and related components in jet engines and gas turbines, improving performance at elevated temperatures. This application is tightly linked to the broader demand for high-efficiency, low-emission engines. Nickel-based superalloys Jet engine Gas turbine
Catalysis: Rhenium compounds serve as catalysts in petroleum refining and petrochemical processing, including reforming and hydrocracking, where they help convert heavy hydrocarbons into lighter, more valuable products. These catalytic roles are part of a broader class of noble- and platinum-group metal–related catalysts used in complex refinery processes. Catalysis Petroleum refining Hydrocracking
Other industrial uses: Re-added to materials to enhance performance in extreme environments, such as certain electrical contacts and specialized alloys used in high-temperature and high-stress settings. Alloy Electrical contact materials

Economic and strategic considerations

Rhenium’s scarcity and the fact that it is typically recovered only as a byproduct mean that its supply is intrinsically linked to the health of the broader mining sector and to demand from aerospace and refining industries. The element has been identified as a critical material by various economies and multilateral bodies concerned with supply chain resilience, market volatility, and strategic industrial capability. Consequently, markets emphasize price signals, long-term contracts, and recycling to mitigate supply risk. The geopolitical and economic implications of rhenium supply have encouraged interest in substitute materials and process efficiencies to reduce dependence on any single source. Critical raw materials Economic geology Aerospace industry

History

Rhenium was named after the Rhine river (Rhenus in Latin, hence the element name) in recognition of its discovery by European chemists in the early 20th century. Its identification and subsequent isolation occurred in the context of intense metallurgical work aimed at understanding and exploiting the properties of molybdenum-rich ores. The naming and classification reflect the broader tradition of linking elemental names to geographic or cultural features. The element’s recognition opened new avenues for high-temperature materials science and refined catalytic processes. Rhine Molybdenum Discovery (chemistry)