Studtite
Encyclopedia
Studtite, chemical formula
[(UO2)O2(H2O)2]·2(H2O) or UO4·4(H2O), is a secondary
uranium
mineral
containing peroxide
formed by the alpha
-radiolysis
of water during formation. It occurs as pale yellow to white needle-like crystal
s often in acicular
, white sprays.
Studtite was originally described by Vaes in 1947 from specimens from Shinkolobwe
, Katanga Copper Crescent, Katanga
(Shaba
), Democratic Republic of Congo, and has since been reported from several other localities. The mineral was named for Franz Edward Studt, an English prospector
and geologist
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 under long-term storage and have been found on the surface of spent nuclear fuel
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
s such as studtite and metastudtite will be important alteration phases of nuclear waste, possibly at the expense of other minerals, such as uranyl oxides
and silicates, 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
sites such as Yucca Mountain nuclear waste repository. Not enough is known about these minerals to know if they will make radioactive waste
s more or less stable.
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
[(UO2)O2(H2O)2]·2(H2O) or UO4·4(H2O), is a secondary
Weathering
Weathering is the breaking down of rocks, soils and minerals as well as artificial materials through contact with the Earth's atmosphere, biota and waters...
uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
containing peroxide
Peroxide
A peroxide is a compound containing an oxygen–oxygen single bond or the peroxide anion .The O−O group is called the peroxide group or peroxo group. In contrast to oxide ions, the oxygen atoms in the peroxide ion have an oxidation state of −1.The simplest stable peroxide is hydrogen peroxide...
formed by the alpha
Alpha particle
Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus, which is classically produced in the process of alpha decay, but may be produced also in other ways and given the same name...
-radiolysis
Radiolysis
Radiolysis is the dissociation of molecules by nuclear radiation. It is the cleavage of one or several chemical bonds resulting from exposure to high-energy flux...
of water during formation. It occurs as pale yellow to white needle-like crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
s often in acicular
Crystal habit
Crystal habit is an overall description of the visible external shape of a mineral. This description can apply to an individual crystal or an assembly of crystals or aggregates....
, white sprays.
Studtite was originally described by Vaes in 1947 from specimens from Shinkolobwe
Shinkolobwe
Shinkolobwe is the name of a town and a mine in the Katanga province of the Democratic Republic of the Congo , located near the larger town of Likasi and about 120 miles northwest of Lubumbashi. The former mine was located in the centre of a 400 kilometre long belt of uranified minerals, stretching...
, Katanga Copper Crescent, Katanga
Katanga Province
Katanga Province is one of the provinces of the Democratic Republic of the Congo. Between 1971 and 1997, its official name was Shaba Province. Under the new constitution, the province was to be replaced by four smaller provinces by February 2009; this did not actually take place.Katanga's regional...
(Shaba
Shaba
Shaba may refer to:* Shaba, Kenya* Shaba National Reserve in Kenya* Shaba Province, name of Katanga Province in present DR Congo between 1971 and 1997* variant spelling of Shebaa`* Shaba Games...
), Democratic Republic of Congo, and has since been reported from several other localities. The mineral was named for Franz Edward Studt, an English prospector
Prospecting
Prospecting is the physical search for minerals, fossils, precious metals or mineral specimens, and is also known as fossicking.Prospecting is a small-scale form of mineral exploration which is an organised, large scale effort undertaken by mineral resource companies to find commercially viable ore...
and geologist
Geologist
A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes and history that has shaped it. Geologists usually engage in studying geology. Geologists, studying more of an applied science than a theoretical one, must approach Geology using...
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 under long-term storage and have been found on the surface of spent nuclear fuel
Nuclear fuel
Nuclear fuel is a material that can be 'consumed' by fission or fusion to derive nuclear energy. Nuclear fuels are the most dense sources of energy available...
stored at the Hanford, Washington nuclear site
Hanford Site
The Hanford Site is a mostly decommissioned nuclear production complex on the Columbia River in the U.S. state of Washington, operated by the United States federal government. The site has been known by many names, including Hanford Works, Hanford Engineer Works or HEW, Hanford Nuclear Reservation...
. It has also been reported that studtite has since formed on the corium
Corium (nuclear reactor)
Corium, also called fuel containing material or lava-like fuel containing material , is a lava-like molten mixture of portions of nuclear reactor core, formed during a nuclear meltdown, the most severe class of a nuclear reactor accident...
lavas that were created during the course of the Chernobyl nuclear plant accident. Thus, there is considerable evidence that uranyl peroxide
Uranyl peroxide
Uranyl peroxide or uranium peroxide hydrate is a pale-yellow, soluble peroxide of uranium. It is found present at one stage of the enriched uranium fuel cycle and in yellowcake prepared via the in situ leaching and resin ion exchange system. This compound, also expressed as:UO3··, is very similar...
s such as studtite and metastudtite will be important alteration phases of nuclear waste, possibly at the expense of other minerals, such as uranyl oxides
Uranium oxide
Uranium oxide is an oxide of the element uranium.The metal uranium forms several oxides:* Uranium dioxide or uranium oxide * Uranium trioxide or uranium oxide...
and silicates, 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
Deep geological repository
A deep geological repository is a nuclear waste repository excavated deep within a stable geologic environment...
sites such as Yucca Mountain nuclear waste repository. Not enough is known about these minerals to know if they will make radioactive waste
Radioactive waste
Radioactive wastes are wastes that contain radioactive material. Radioactive wastes are usually by-products of nuclear power generation and other applications of nuclear fission or nuclear technology, such as research and medicine...
s more or less stable.