Lepidolite
Lepidolite is the name for a rather seldom occurring, unspecified mixed crystal from the mineral series polylithionite - trilithionite within the group of mica with the general chemical composition K (Li, Al) 3 [(F, OH) 2 | (Si, Al) 4 O 10 ].
Lepidolite developed predominantly white, gray to pink-violet mineral aggregates in the form of closely superposed, flaky, bladed crystal tablets or spherical, grapey spherulites on the gap faces a bright pearl gloss exhibited. The pink color is caused by a low content of Mn 2+ . In pegmatite dikes , lithium pegmatite can be found at various sites , in which the smallest lepidolite mica with a typical color from light pink to dark red (<1 mm) can be seen. Occasionally white lithium pegmatite is also found, which (in addition to the mica effect) can be detected through the presence of rubidium .
The minerals phlogopite and especially muscovite look very similar to lepidolite. The synonym lepidolite is therefore occasionally misleading .
Etymology and history
The mica was originally named Lilalith (Lilastein) by its discoverer Nicolaus Poda von Neuhaus . However, this name was criticized by Martin Heinrich Klaproth as a rather joking designation and felt to be unsustainable in the professional world, since color names would be unsuitable as a generic name and the word also a hybrid with Arabic ( purple = ' lilac ' or ' lilac-colored ') and Greek components be. He therefore renamed it lepidolite, after the Greek words λεπιδιον lepidion for "scaly" and lithos for λίθος lithos = "stone". Put together, the name has the meaning "flaky stone" or "shed stone".
In 1861 Robert Bunsen and Gustav Kirchhoff discovered the alkali metal rubidium by spectroscopy , which occurs as a substitute for a small part of the potassium in lepidolite.
Crystal structure
Lepidolite crystallizes polytype in monoclinic symmetry , which are called Lepidolite-1M , Lepidolite-2M 1 , Lepidolite-2M 2 and Lepidolite-3M 2 and in trigonal symmetry with the name Lepidolite-3T .
| Polytype | Crystal system | Space group | Lattice parameters and formula units per unit cell (Z) |
|---|---|---|---|
| Lepidolite-1M | monoclinic | C 2 / m (No. 12) | a = 5.21 Å ; b = 9.01 Å; c = 10.15 Å and β = 100.8 ° and Z = 2 |
| Lepidolite-2M 1 | C 2 / c (No. 15) | a = 5.20 Å ; b = 9.03 Å; c = 19.97 Å and β = 95.4 ° and Z = 4 | |
| Lepidolite-2M 2 | C 2 / c (No. 15) | a = 9.02 Å ; b = 5.20 Å; c = 20.17 Å and β = 99.5 ° and Z = 4 | |
| Lepidolite-3M 2 | C 2 (No. 5) | a = 5.24 Å ; b = 9.07 Å; c = 59.76 Å and β = 92.6 ° and Z = 12 | |
| Lepidolite-3T | trigonal | P 3 1 12 (No. 151) or P 3 2 12 (No. 153) | a = 5.20 Å and c = 29.76 Å and Z = 3 |
properties
Some lepidolite samples show triboluminescence .
Education and Locations
Lepidolites are mainly formed by hydrothermal processes in granite pegmatites . It occurs less often than the minerals spodumene and the tourmaline group as well as their varieties, but occurs in nature mostly in paragenesis with them. Other parageneses include quartz , petalite and various feldspars , but also ore minerals such as cassiterite and tantalite-Mn .
So far (as of 2010) lepidolite has been detected at almost 550 sites worldwide, including in Afghanistan , Algeria , Antarctica , Argentina , Ethiopia , Australia , Belgium , Bolivia , Brazil , China , Germany , Finland , France , French Guiana , Greenland , Italy , Japan , Canada , Kazakhstan , North and South Korea , Madagascar , Macedonia , Mexico , Mongolia , Mozambique , Myanmar , Namibia , Nepal , Norway , Austria , Pakistan , Portugal , Russia , Zambia , Sweden , Switzerland, Zimbabwe , Spain Slovakia , Swaziland , Tajikistan , Thailand Czech Republic , Turkey , Uzbekistan , the United Kingdom (Great Britain), the United States of America (USA) and Vietnam .
use
Due to its high lithium content, lepidolite is used as an ore to extract lithium .
Lepidolite stones are also used as a decorative element in aquariums .
See also
literature
- Lepidolite . 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; 79 kB ; accessed on April 29, 2019]).
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 749–750 (first edition: 1891).
- Martin Okrusch, Siegfried Matthes: Mineralogy: An introduction to special mineralogy, petrology and deposit science . 7th edition. Springer Verlag, Berlin, Heidelberg, New York 2005, ISBN 3-540-23812-3 , pp. 103-104 .
- Chris Pellant: Stones and Minerals . 1st edition. Dorling Kindersley Limited, 1992, ISBN 978-3-8310-0892-6 , pp. 160 .
- Rudulf Duda, Lubos Rejl: Minerals Guide - Minerals, Rocks, Gems . Franckh-Kosmos Verlag, 2002, ISBN 978-3-440-08471-7 , pp. 217 .
Web links
- Mineral Atlas: Lepidolite (Wiki)
Individual evidence
- ^ A b 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. 667-668 (English).
- ↑ Lepidolite. In: mindat.org. Hudson Institute of Mineralogy, accessed June 17, 2019 .
- ↑ TO Poda: From the Lilalith . In: Johann Ehrenreich von Fichtel (Ed.): Mineralogical essays . Mathias Andreas Schmidt, imperial and royal book printer, Vienna 1794, p. 226–236 ( available online at rruff.info [PDF; 277 kB ; accessed on April 29, 2019]).
- ↑ Hans Lüschen: The names of the stones. The mineral kingdom in the mirror of language . 2nd Edition. Ott Verlag, Thun 1979, ISBN 3-7225-6265-1 , p. 264 .
- ↑ Mineral Encyclopedia - Lepidolite ( Memento from March 4, 2016 in the Internet Archive )
- ↑ Find location list for lepidolite in the Mineralienatlas and Mindat