Ichnusaite is a very rarely found mineral. Ichnusaite is a natural compound of thorium and molybdenum with the formula Th(MoO4)2·3H2O. It was discovered in Su Seinargiu, Sarroch, Cagliari, Sardegna, Italy in 2013.
This locality is also a place of discovery of the second natural thorium molybdate – nuragheite.
General Information
- Category: Molybdate minerals
- Formula: Th(MoO4)23H2O
- Crystal system: Monoclinic
- Crystal class: Prismatic (2/m) (same H-M symbol)
Fig: Ichnusaite
Properties
- Color: Colorless
- Cleavage: {100}, perfect
- Tenacity: Brittle
- Luster: Pearly adamantine
Occurrence
Muscovite, nuragheite, and xenotime-(Y) are the associates of ichnusaite. It is a secondary mineral in vugs in hydrothermal veins cutting porphyritic granite.
Association: Nuragheite, muscovite, xenotime-(Y), quartz, molybdenite
Crystal structure
The main features of the crystal structure of ichnusaite are:
- electroneutral Th(MoO4)2(H2O)2 (100) sheets
- ThO7(H2O)2 and MoO4 polyhedra polymerize to give the above sheets
- sheets are stacked along [100] and held by hydrogen bonds
Information Source:
