Jeremejevite
| Jeremejevite | |
|---|---|
|
Jeremejevite colorless to light blue crystal spray of prisms from Ochtendung, Eifel, Germany | |
| 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 from the Pamir Mountains of Tajikistan, Namibia and the Eifel district, Germany.[3]
References
- ↑ Jeremjevite on Mindat.org
- ↑ Jeremejevite on Webmineral.com
- 1 2 3 Handbook of Mineralogy
- ↑ 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.
Blue jeremejevite in rare, clear crystal form. Image width: 1.5 mm.
Faceted jeremejevite, 0.14 ct, Namibia
Faceted jeremejevite, light green, 0.93 ct
Faceted jeremejevite, golden yellow, 1.97 and 0.84 ct
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