Jeremejevite

Jeremejevite
General
Category Borate mineral
Formula
(repeating unit)		 Al6B5O15(F,OH)3
Strunz classification 6.AB.15
Crystal system Hexagonal
Crystal class Dipyramidal class (6/m)
H-M symbol: (6/m)
Space group P63/m
Unit cell a = 8.5591(3),
c = 8.1814(6) [Å]; Z = 2
Identification
Color Colorless, white, yellowish, blue
Crystal habit Prismatic
Cleavage None observed
Fracture Conchoidal
Mohs scale hardness 6.5 - 7.5
Luster Vitreous
Streak White
Diaphaneity Transparent
Specific gravity 3.28 - 3.31
Optical properties Uniaxial (-)
Refractive index nω = 1.653 nε = 1.640
Birefringence 0.0130
Pleochroism Colorless - light blue-violet
Other characteristics Piezoelectric
References [1][2][3]

Jeremejevite is a rare aluminium borate mineral with variable fluoride and hydroxide ions. Its chemical formula is Al6B5O15(F,OH)3.

It was first described in 1883[4] for an occurrence on Mt. Soktui, Nerschinsk district, Adun-Chilon Mountains, Siberia. It was named after Russian mineralogist Pavel Vladimirovich Eremeev (Jeremejev, German) (1830–1899).[3]

It occurs as a late hydrothermal phase in granitic pegmatites in association with albite, tourmaline, quartz and rarely gypsum. It has also been reported in the Pamir Mountains of Tajikistan, Namibia and the Eifel district, Germany.[3]

Blue jeremejevite in rare, clear crystal form. Image width: 1.5 mm.

References

  1. ↑ Jeremjevite on Mindat.org
  2. ↑ Jeremejevite on Webmineral.com
  3. 1 2 3 Handbook of Mineralogy
  4. ↑ Damour A. Note sur un borate d'alumine cristallisé de la Siberie. Nouvelle espèce minerale // Bulletin de la Societe mineralogique de France. 1883. 6. N 1. P. 20-23.
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