Nuragheite

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]

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]

Occurrence and association

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

Notes on chemistry

Nuragheite is chemically pure.[2]

Crystal structure

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

  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. 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. "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.
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