Schäferite

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Schäferite
General
Category Mineral
Chemical formula Ca2NaMg2[VO4]3
Strunz classification 8.AC.25
Crystal symmetry Isometric hexoctahedral
H-M symbol: (4/m32/m)
Space group: I a3d
Unit cell a = 12.427 Å, Z = 8
Identification
Molar mass 496.57 g
Color Red, orange-red
Crystal habit Octahedral crystals
Cleavage None
Fracture Conchoidal
Luster Vitreous
Streak Yellow
Diaphaneity Transparent
Optical properties Isotropic
Refractive index n = 1.96
References [1][2]

Schäferite is a rare vanadate mineral with chemical formula Ca2NaMg2[VO4]3. Schäferite is isometric, which means that it has three axes of equal length and 90° angles between the axes.[3] Schäferite belongs to the optical class Isotropic, meaning that the velocity of light is the same no matter which direction the light passes through.[2]

It was named after Helmut Schäfer (b. 1931) who discovered it in a quarry on the Bellerberg volcano in Germany.[1] It is a rare earth mineral that is found only in the Eifel Mountains volcanic area near Mayen, Laacher See district of Germany.[1] It occurs within a xenolith in a leucite tephrite. It is the magnesium analogue of palenzonaite and is a member of the garnet group.[2]

[edit] References

  1. ^ a b c Ralph, Jolyon and Ida Chau, 17 August 2010, "Schäferite." http://www.mindat.org/min-7279.html. Accessed 27 September 2010.
  2. ^ a b c Barthelmy, David, 1997-2010, “Schäferite Mineral Data.” http://www.webmineral.com/data/Schaferite.shtml. Accessed 27 September 2010.
  3. ^ Verlagsbuchhandlung, E.S. (1999) Schäferite, a new vanadium garnet. Neues Jahrbuch Fur Mineralogie,1, 123-134.
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