Studtite

Studtite, empirical formula (UO₂)O₂·4(H₂O), is a secondary uranium mineral containing peroxide formed by the alpha-radiolysis of water during formation. It occurs as white yellow needle-like crystals often in acicular, white sprays. Studtite was originally described by Vaes in 1947 from specimens from Shinkolobwe, Democratic Republic of Congo, and has since been reported from several other localities. The mineral was named for Franz Edward Studt, a Belgian prospector and geologist.

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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 unique and fascinating because they 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, Wash., nuclear site. It has also been reported that studtite has since formed on the lavas that were created during the course of the Chernobyl nuclear plant accident. Thus, there is considerable evidence that uranyl peroxides 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. Not enough is known about these minerals to know if they will make radioactive wastes more stable or less.

References

• Studtite Mineral Data
• Studtite: The first structure of a peroxide mineral
• Unusual Minerals Formed on Stored Nuclear Waste