Nuragheite is a rare
natural
thorium
Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high ...
molybdate
In chemistry a molybdate is a compound containing an oxoanion with molybdenum in its highest oxidation state of 6. Molybdenum can form a very large range of such oxoanions which can be discrete structures or polymeric extended structures, althou ...
, formula Th(MoO
4)
2·H
2O, discovered in Su Seinargiu,
Sarroch,
Cagliari,
Sardegna
Sardinia ( ; it, Sardegna, label=Italian, Corsican and Tabarchino ; sc, Sardigna , sdc, Sardhigna; french: Sardaigne; sdn, Saldigna; ca, Sardenya, label=Algherese and Catalan) is the second-largest island in the Mediterranean Sea, after ...
, Italy.
[Orlandi, P., Biagioni, C., Bindi, L., and Merlino, S., 2015. Nuragheite, Th(MoO4)2·H2O, the second natural thorium molybdate and its relationships to ichnusaite and synthetic Th(MoO4)2. American Mineralogist 100(1), 267-273] This locality is also a place of discovery of the other thorium molybdate -
ichnusaite, which is a trihydrate.
Occurrence and association
Nuragheite is a part of
molybdenum-
bismuth
Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs ...
mineralization. It coexists with
ichnusaite,
muscovite
Muscovite (also known as common mica, isinglass, or potash mica) is a hydrated phyllosilicate mineral of aluminium and potassium with formula K Al2(Al Si3 O10)( F,O H)2, or ( KF)2( Al2O3)3( SiO2)6( H2O). It has a highly perfect basal cleavag ...
, and
xenotime-(Y).
[
]
Notes on chemistry
Nuragheite is chemically pure.[
]
Crystal structure
The crystal structure of nuragheite is composed of (100) layers with IXTh-centered polyhedra and Mo-centered tetrahedra.[ It is thus similar to that of ichnusaite.
]
References
{{reflist
Thorium minerals
Molybdate minerals
Monoclinic minerals
Minerals in space group 14