| Jeremejevite | |
|---|---|
Jeremjevite colorless needles - Ochtendung, Eifel, Germany |
|
| General | |
| Category | Borate |
| Chemical formula | Al6B5O15(F,OH)3 |
| Strunz classification | 06.AB.15 |
| Identification | |
| Color | clear, white, yellowish, blue |
| Crystal habit | Prismatic |
| Crystal system | Hexagonal - Dipyramidal |
| 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.
It was first described in 1883 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 from the Pamir Mountains of Tajikistan, Namibia and the Eifel district, Germany.[3]