Studtite,

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

UO₂)O₂(H₂O)₂�2(H₂O) or UO₄·4(H₂O), is a secondary

uranium Uranium is a chemical element; it has chemical symbol, symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Ura ...

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

containing

peroxide In chemistry, peroxides are a group of Chemical compound, compounds with the structure , where the R's represent a radical (a portion of a complete molecule; not necessarily a free radical) and O's are single oxygen atoms. Oxygen atoms are joined ...

formed by the

alpha Alpha (uppercase , lowercase ) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter ''aleph'' , whose name comes from the West Semitic word for ' ...

radiolysis Radiolysis is the dissociation of molecules by ionizing radiation. It is the cleavage of one or several chemical bonds resulting from exposure to high-energy flux. The radiation in this context is associated with ionizing radiation; radiolysis is ...

of water during formation. It occurs as pale yellow to white needle-like

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

s often in acicular, white sprays. Studtite was originally described by Vaes in 1947Annales de la Société Géologique de Belgique - 1947 - pp B212 to B226- J.F. Vaes - Six nouveaux minéraux d'urane provenant de Shinkolobwe (Katanga) - from specimens from

Shinkolobwe Shinkolobwe, or Kasolo, or Chinkolobew, or Shainkolobwe, was a radium and uranium mine in the Haut-Katanga Province of the Democratic Republic of the Congo (DRC), located west of Likasi (formerly Jadotville), south of Kambove, and about northwe ...

, Katanga Copper Crescent, Katanga (Shaba),

Democratic Republic of Congo The Democratic Republic of the Congo (DRC), also known as the DR Congo, Congo-Kinshasa, or simply the Congo (the last ambiguously also referring to the neighbouring Republic of the Congo), is a country in Central Africa. By land area, it is t ...

, and has since been reported from several other localities. The mineral was named for Franz Edward Studt, an English

prospector Prospector may refer to: Space exploration * Prospector (spacecraft), a planned lunar probe, canceled in 1962 * ''Lunar Prospector'', a NASA spacecraft Trains * Prospector (train), a passenger train operated by the Denver & Rio Grande Western ra ...

and

geologist A geologist is a scientist who studies the structure, composition, and History of Earth, history of Earth. Geologists incorporate techniques from physics, chemistry, biology, mathematics, and geography to perform research in the Field research, ...

who was working for the Belgians. When exposed to air studtite converts over a short time to the metastudtite UO₄·2(H₂O) form. Despite their apparent chemical simplicity, these two uranyl species are the only reported peroxide minerals. They may also be readily formed on the surface of

nuclear waste Radioactive waste is a type of hazardous waste that contains radioactive material. It is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, nuclear decommissioning, rare-earth mining, and nuclear ...

under long-term storage and have been found on the surface of spent

nuclear fuel Nuclear fuel refers to any substance, typically fissile material, which is used by nuclear power stations or other atomic nucleus, nuclear devices to generate energy. Oxide fuel For fission reactors, the fuel (typically based on uranium) is ...

stored at the Hanford, Washington nuclear site. * It has also been reported that studtite has since formed on the corium ''lavas'' that were created during the course of the Chernobyl nuclear plant accident. Thus, there is considerable evidence that

uranyl peroxide Uranyl peroxide or uranium peroxide hydrate (UO4·nH2O) is a pale-yellow, soluble peroxide of uranium. It is found to be present at one stage of the enriched uranium fuel cycle and in yellowcake prepared via the ''in situ'' leaching and resin ion e ...

s such as studtite and metastudtite will be important alteration phases of

, possibly at the expense of other minerals, such as uranyl oxides and

silicates A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used for an ...

, which have been more thoroughly studied and are better understood. The formation of these minerals may impact the long-term performance of

deep geological repository A deep geological repository is a way of storing hazardous or radioactive waste within a stable geologic environment, typically 200–1,000 m below the surface of the earth. It entails a combination of waste form, waste package, engineered seals ...

sites such as

Yucca Mountain nuclear waste repository The Yucca Mountain Nuclear Waste Repository, as designated by the Nuclear Waste Policy Act amendments of 1987, is a proposed deep geological repository storage facility within Yucca Mountain for spent nuclear fuel and other high-level radioact ...

. Due to insufficient information about these minerals it is unknown if they will make

radioactive waste Radioactive waste is a type of hazardous waste that contains radioactive material. It is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, nuclear decommissioning, rare-earth mining, and nuclear ...

s more or less stable, but the presence of studtite and metastudtite provides a pathway for mobilizing insoluble U(IV) from the corroding fuel surface into soluble

uranyl The uranyl ion with the chemical formula has a linear structure with short U–O bonds, indicative of the presence of multiple bonds between uranium and oxygen, with uranium in the oxidation state +6. Four or more ligands may be bound to the u ...

species.

References

Uranium(VI) minerals Oxide minerals Radioactive waste Monoclinic minerals Minerals in space group 12 {{Oxide-mineral-stub