Nuragheite

Nuragheite
General
Category Molybdate minerals
Formula
(repeating unit)		 Th(MoO4)2·H2O
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group P21/c
Unit cell a = 7.36, b = 10.54
c = 9.49 [Å], β=91.88° (approximated)
Identification
Color Colorless
Crystal habit Thin tablets
Cleavage {100}, perfect
Tenacity Brittle
Luster Pearly adamantine
Streak White
Specific gravity 5.15 (calc., approximated)
References [1][2]

Nuragheite is a rare[2] natural thorium molybdate, formula Th(MoO4)2·H2O, discovered in Su Seinargiu, Sarroch, Cagliari, Sardegna, Italy.[1] This locality is also a place of discovery of the other thorium molybdate - ichnusaite, which is a trihydrate.[3]

Occurrence and association

Nuragheite is a part of molybdenum-bismuth mineralization. It coexists with ichnusaite, muscovite, and xenotime-(Y).[1]

Notes on chemistry

Nuragheite is chemically pure.[1]

Crystal structure

The crystal structure of nuragheite is composed of (100) layers with IXTh-centered polyhedra and Mo-centered tetrahedra.[1] It is thus similar to that of ichnusaite.

References

  1. 1 2 3 4 5 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
  2. 1 2 "Nuragheite - Mindat.org". Mindat.org. Retrieved 2016-03-12.
  3. ↑ 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.
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