Schiavinatoite Explained

Schiavinatoite
Category:Borate, Oxide
Imasymbol:Shv[1]
Strunz:6.AC.15
System:Tetragonal
Class:Ditetragonal dipyramidal (4/mmm)
H-M symbol: (4/m 2/m 2/m)
Symmetry:I41/amd
Unit Cell:a = 6.22, c = 5.49 [Å] (approximated); Z = 4
Color:Colorless
Habit:zones of prismatic dipyramidal crystals (intergrown with béhierite)
Mohs:8
Luster:Vitreous
Refractive:n=2.30
Opticalprop:Uniaxial (+)
Birefringence:Yes
Streak:White
Density:6.55
References:[2]

Schiavinatoite is a very rare mineral,[3] the niobium endmember of a borate solid solution with the chemical formula . The tantalum analogue is béhierite. [4] Schiavinatoite is classified as monoborate. It contains tetrahedral borate anion instead of planar BO3 group, which is more common among minerals. Schiavinatoite is one of the most simple niobium minerals. Both minerals possess zircon-type structure (tetragonal, space group I41/amd) and occur in pegmatites. Schiavinatoite and nioboholtite are minerals with essential niobium and boron.[5]

Occurrence and association

Schiavinatoite was detected in miaroles of a pegmatite at Antsongombato, Madagascar. It coexists with an apatite-group mineral, béhierite, danburite, elbaiteliddicoatite, feldspar, pollucite, quartz, rhodizite, and spodumene.[2]

Crystal structure

The main facts about schiavinatoite's structure:[4]

Notes and References

  1. Warr. L.N.. 2021. IMA–CNMNC approved mineral symbols. Mineralogical Magazine. 85. 3. 291–320. 10.1180/mgm.2021.43. 2021MinM...85..291W. 235729616. free.
  2. Web site: Schiavinatoite - Handbook of Mineralogy . Handbookofmineralogy.org . 2016-03-12.
  3. Web site: Schiavinatoite: Schiavinatoite mineral information and data . Mindat.org . 2016-03-02.
  4. Demartin, F., Diella, V., Gramaccioli, C.M., and Pezzotta, F., 2001. Schiavinatoite,, the Nb analogue of behierite. European Journal of Mineralogy 13, 159-165
  5. Web site: Nioboholtite: Nioboholtite mineral information and data . Mindat.org . 2016-03-03.