Jeremeevit
| Jeremeevit | |
|---|---|
 |
|
| General and classification | |
| other names |
Eichwaldite |
| chemical formula |
|
|
Mineral class (and possibly department) |
Borates (formerly "carbonates, nitrates and borates", see classification ) |
|
System no. to Strunz and to Dana |
6.AB.15 ( 8th edition : Vc / A.01a) 08.25.01.01 |
| Similar minerals | Fluoborite, hydroxyl borite |
| Crystallographic Data | |
| Crystal system | hexagonal |
| Crystal class ; symbol | hexagonal dipyramidal; 6 / m |
| Space group | P 6 3 / m (No. 176) |
| Lattice parameters | a = 8.56 Å ; c = 8.18 Å |
| Formula units | Z = 2 |
| Frequent crystal faces | {11 2 0} |
| Physical Properties | |
| Mohs hardness | 6.5 to 7.5 |
| Density (g / cm 3 ) | 3.28 to 3.29 |
| Cleavage | is missing |
| Break ; Tenacity | shell-like |
| colour | colorless, white, light yellowish brown, light to dark blue |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n ω = 1.653 n ε = 1.640 |
| Birefringence | δ = 0.013 |
| Optical character | uniaxial negative, possibly also abnormally biaxial negative in zoned crystals |
| Axis angle | 2V = 18 ° to 33 ° |
| Pleochroism | colorless to light blue-violet |
| Other properties | |
| Special features | Piezoelectricity |
Jeremejewit is a rarely occurring mineral from the mineral class of " borates " (formerly "carbonates, nitrates and borates", see classification ) with the chemical composition Al 6 [(F, OH) 3 | (BO 3 ) 5 ] and therefore chemically an aluminum borate with additional fluorine or hydroxide ions .
Jeremejewit crystallizes in the hexagonal crystal system and develops mostly needle-like to prismatic crystals with a hexagonal habit with a glass-like sheen on the surfaces. In its pure form, Jeremejewit is colorless and transparent. However, due to multiple light refraction due to lattice defects or polycrystalline formation, it can also be translucent white and, due to foreign admixtures, take on a light yellowish-brown or light to dark blue color.
Etymology and history
The first colorless crystals were found in the pegmatite of Soktuj Gora in the Adun Cholon Mountains near Nertschinsk in the Russian region of Transbaikalia and were described in 1883 by the French mineralogist Augustin Alexis Damour , who named the mineral in honor of the Russian mineralogist, crystallographer and engineer Pavel Vladimirovich Jeremejew ( 1830–1899) named after him.
The type material of the mineral is registered in the Mining Institute of Saint Petersburg in Russia under catalog no. 412/1 kept.
Since Jeremejewite was known and recognized as an independent mineral type long before the founding of the International Mineralogical Association (IMA), this was adopted by its Commission on New Minerals, Nomenclature and Classification (CNMNC) and referred to Jeremejewite as a so-called grandfathered mineral .
classification
In the outdated 8th edition of the mineral classification according to Strunz , the Jeremejewit belonged to the common mineral class of "carbonates, nitrates and borates " and there to the department of "island borates (Nesoborates)", where it was the only member of the unnamed subgroup Vc / A.01a within the "Jeremejewit-Kotoit-Gruppe" ( Vc / A.01 ) formed.
In the Lapis mineral directory according to Stefan Weiß, which, out of consideration for private collectors and institutional collections, is still based on this old form of Karl Hugo Strunz's system , the mineral was given the system and mineral number. V / G.05-30 . In the "Lapis Classification" this also corresponds to the "island borates" department where Jeremejewit with Chubarovit , Fluoborit , Hydroxylborit , Jacquesdietrichit , Karlit , Mengxianminit and Painite forms an independent but unnamed group (as of 2018).
The 9th edition of the Strunz'schen mineral systematics, which has been valid since 2001 and updated by the IMA until 2009, assigns the Jeremejewit to the newly defined class of "borates" and there in the department of "monoborates". This section is further subdivided according to the structure of the borate complex and the possible presence of further anions , so that the mineral according to its composition in the sub-section “BO 3 with additional anions; 1 (Δ) + OH etc. ”is to be found, where it is the only member of the unnamed group 6.AB.15 .
The systematics of minerals according to Dana assigns the Jeremejewit like the old Strunz'sche systematics in the class of "carbonates, nitrates and borates", there however in the department of "anhydrous borates with hydroxyl or halogen". Here he is the only member of the unnamed group 08/25/01 within the sub-section “ Anhydrous borates with hydroxyl or halogen ”.
Crystal structure
Jeremejewit crystallizes hexagonally in the space group P 6 3 / m (space group no. 176) with the lattice parameters a = 8.56 Å and c = 8.18 Å as well as 2 formula units per unit cell .
properties
morphology
Most of the intensely blue Jeremejevites have no exact edges or crystal faces. Jeremejewite crystals can be up to approx. 6 cm long and approx. 5 mm thick, but can also have a needle-like design with a diameter of approx. 1 mm. Many crystals become a bit narrower towards the top. Larger crystals that are still on the matrix are rare. The reason for this is still unknown.
Physical Properties
Jeremejewit has piezoelectric properties, which means that, as with the well-known quartz, an electrical voltage builds up in the crystal due to changing elastic deformation .
Education and Locations
Jeremejewit is formed by hydrothermal processes in granitic pegmatites . Accompanying minerals include albite , tourmaline , quartz and gypsum .
As a rare mineral formation, Jeremejewit could only be detected in a few places, whereby 16 sites have been documented so far. Its type locality Soktuj Gora is the only known site in Russia to date .
In Germany, the mineral has so far only been found in Rhineland-Palatinate , more precisely in the “Kahlenberg” ( Auf'm Kopp ) opencast mine near Oberstadtfeld , on Emmelberg near Üdersdorf and on Niveligsberg near Drees in the Vulkaneifel ; the quarry Herchenhainer mountain in Burgbrohl in the district of Ahrweiler and on Nickenicher saddle at Eich (Andernach) , the Rothenberg at Bell and to the point heads in Ochtendung found in Mayen-Koblenz.
Other well-known sites are the "Pantahole Mine" near Momeik in the Burmese Mandalay Division , Madagascar , several places in the Namibian region of Erongo as well as the Rangkul pegmatite field and the Vez Dara valley near Chorugh ( Khorog ) in the Berg-Badachschan province of Tajikistan (as of 2020).
Use as a gem stone
Jeremejewite crystals can be colorless, light yellowish brown or light to dark blue. Greenish and purple stones are also known. The rarest and most valuable color is a rich cornflower blue. Light or medium blue crystals are also very sought after. Some colorless or light blue crystals gradually turn a deeper blue in the lower area.
As with other gemstones , the value of a Jeremejewite depends primarily on its purity, color and weight: the most valuable stones should be eye-clean or flawless, have an intense cornflower blue color and be large (> 1 carat ). Jeremejewite are usually faceted baguette or emerald cut, but are also offered oval faceted.
slightly yellowish-brownish Jeremejewite, 1.97 ct and 0.84 ct, from Mogok, Myanmar
Blue Jeremejewit, 0.80 ct, from Namibia
Slightly greenish Jeremejewite, 0.93 ct, from Namibia
See also
literature
- AA Damour: Note sur un borate d'alumine cristallisé de la Siberie. Nouvelle espèce minerale . In: Bulletin de la Societe mineralogique de France . tape 6 , no. 1 , 1883, p. 20–23 (French, rruff.info [PDF; 154 kB ; accessed on June 21, 2020]).
- Eugene E. Foord, Richard C. Erd, Graham R. Hunt: New data for jeremejevite . In: The Canadian Mineralogist . tape 19 , 1981, p. 303–310 (English, rruff.info [PDF; 617 kB ; accessed on June 21, 2020]).
Web links
- Jeremeevit. In: Mineralienatlas Lexikon. Stefan Schorn u. a., accessed on June 21, 2020 .
- Jeremejevite. In: mindat.org. Hudson Institute of Mineralogy, accessed June 21, 2020 .
- Jeremejevite search results. In: rruff.info. Database of Raman spectroscopy, X-ray diffraction and chemistry of minerals (RRUFF), accessed on June 21, 2020 .
- American-Mineralogist-Crystal-Structure-Database - Jeremejevite. In: rruff.geo.arizona.edu. Accessed June 21, 2020 (English).
- Michael RW Peters: Pictures of raw and polished Jeremejewites. In: Realgems.org. September 30, 2012, accessed June 21, 2020 .
Individual evidence
- ^ Karl Hugo Strunz , Christel Tennyson : Mineralogical tables . 8th edition. Academic publishing company Geest & Portig KG, Leipzig 1982, p. 250-251 .
- ↑ a b Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: March 2020. (PDF; 2.44 MB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, March 2020, accessed June 21, 2020 .
- ^ David Barthelmy: Jeremejevite Mineral Data. In: webmineral.com. Retrieved June 20, 2020 (English).
- ↑ a b c d Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 331 (English).
- ↑ a b c d e f g h i Jeremejevite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 68 kB ; accessed on June 20, 2020]).
- ↑ a b c Jeremejevite. In: mindat.org. Hudson Institute of Mineralogy, accessed June 21, 2020 .
- ^ AA Damour: Note sur un borate d'alumine cristallisé de la Siberie. Nouvelle espèce minerale . In: Bulletin de la Societe mineralogique de France . tape 6 , no. 1 , 1883, p. 20–23 (French, rruff.info [PDF; 154 kB ; accessed on June 21, 2020]).
- ↑ Catalog of Type Mineral Specimens - J. (PDF 40 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed June 21, 2020 .
- ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
- ↑ Ernest H. Nickel , Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF; 1.82 MB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed June 21, 2020 .
- ↑ locality list and number of Jeremejewit. In: Mineralienatlas Lexikon. Stefan Schorn u. a., accessed on June 21, 2020 .
- ↑ a b List of locations for the Mineralienatlas and Mindat , accessed on June 21, 2020.
- ↑ Michael RW Peters: Pictures to raw and polished Jeremejewiten. In: Realgems.org. September 30, 2012, accessed June 21, 2020 .