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Nuragheite

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Nuragheite
General
CategoryMolybdate minerals
Formula
(repeating unit)
Th(MoO4)2·H2O
IMA symbolNur[1]
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupP21/c
Unit cella = 7.36, b = 10.54
c = 9.49 [Å], β=91.88° (approximated)
Identification
ColorColorless
Crystal habitThin tablets
Cleavage{100}, perfect
TenacityBrittle
LusterPearly adamantine
StreakWhite
Specific gravity5.15 (calc., approximated)
Other characteristics Radioactive
References[2][3]

Nuragheite is a rare[3] natural thorium molybdate, formula Th(MoO4)2·H2O, discovered in Su Seinargiu, Sarroch, Cagliari, Sardegna, Italy.[2] This locality is also a place of discovery of the other thorium molybdate - ichnusaite, which is a trihydrate.[4]

Occurrence and association

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Nuragheite is a part of molybdenum-bismuth mineralization. It coexists with ichnusaite, muscovite, and xenotime-(Y).[2]

Notes on chemistry

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Nuragheite is chemically pure.[2]

Crystal structure

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The crystal structure of nuragheite is composed of (100) layers with IXTh-centered polyhedra and Mo-centered tetrahedra.[2] It is thus similar to that of ichnusaite.

References

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  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b c d e 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
  3. ^ a b "Nuragheite - Mindat.org". Mindat.org. Retrieved 2016-03-12.
  4. ^ Orlandi, Paolo; Biagioni, Cristian; Bindi, Luca; Nestola, Fabrizio (2014-10-01). "Ichnusaite, Th(MoO4)2·3H2O, the first natural thorium molybdate: Occurrence, description, and crystal structure". American Mineralogist. 99 (10): 2089–2094. doi:10.2138/am-2014-4844. ISSN 0003-004X. S2CID 97061833. Archived from the original on 2016-05-21. Retrieved 2016-03-12.