Amblygonite
| Amblygonite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | (Li, Na) Al [(F, OH) | PO 4 ] |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.BB.05 ( 8th edition : VII / B.02) 05.41.08.01 |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triclinic pinacoidal; 1 |
| Room group (no.) | P 1 (No. 2) |
| Lattice parameters |
a = 6.64 Å ; b = 7.74 Å; c = 6.91 Å α = 90.35 °; β = 117.33 °; γ = 91.01 ° |
| Formula units | Z = 4 |
| Twinning | lamellar according to (100) and ( 1 01) |
| Physical Properties | |
| Mohs hardness | 5.5 to 6 |
| Density (g / cm 3 ) | 3.04 to 3.11 |
| Cleavage | perfect after {100}, good after {110}, clear after {011}, indistinct after {001} |
| Break ; Tenacity | shell-like to uneven |
| colour | white, pale yellow, pink, gray, greenish, bluish |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss, fat gloss, matt |
| Crystal optics | |
| Refractive indices |
n α = 1.577 to 1.591 n β = 1.592 to 1.605 n γ = 1.596 to 1.613 |
| Birefringence | δ = 0.019 to 0.022 |
| Optical character | biaxial negative |
| Axis angle | 2V = 107 to 129.5 ° |
Amblygonite is a rather rare mineral from the mineral class of anhydrous phosphates with foreign anions. It crystallizes in the triclinic crystal system with the chemical composition (Li, Na) Al [(F, OH) | PO 4 ] and develops mostly short, prismatic crystals , but also granular to massive aggregates that are either colorless or white, gray, pink, yellowish, greenish or bluish in color.
Etymology and history
The name Amblygonit is a composition of the Greek words άμβλύς ( amblys ) for "blunt" and γόνυ ( Goni ) for "angle" and refers to the fact that Amblygonit in different directions, each with different angles but different than 90 °, splits .
It was first described in 1817 by August Breithaupt .
classification
In the old classification of minerals by Strunz (8th edition) of Amblygonit is part of the department of "anhydrous phosphates with foreign anions " and forms there with Griphit , Montebrasite , Natromontebrasit , Tancoit and Tavorit a group. Since the new systematics of minerals according to Strunz (9th edition) , this department has been more precisely subdivided according to the size of the cations and the mineral is now with montebrasite and tavorite in the subdivision of "anhydrous phosphates with foreign anions and only medium-sized cations, (OH , etc.): RO 4 "less or equal" 1: 1 "to be found.
The systematics of minerals according to Dana also assigns amblygonite to the division of “anhydrous phosphates”, but there into the sub-division “with hydroxyl (groups) or halogen (s) with the composition (AB) 2 (XO 4 ) Z q ".
Crystal structure
| Crystal system | triclinic | |
| Space group | P 1 | |
|
Lattice parameter (unit cell ) |
a = 6.64 Å b = 7.74 Å c = 6.91 Å |
α = 90.35 ° β = 117.33 ° γ = 91.01 ° |
| Number (Z) of the formula units |
Z = 4 | |
Amblygonite crystallizes in the triclinic crystal system in the space group P 1 with the lattice parameters a = 6.64 Å , b = 7.74 Å and c = 6.91 Å; α = 90.35 °, β = 117.33 ° and γ = 91.01 ° as well as four formula units per unit cell and is isotypic to Tavorite , i.e. H. these two minerals have the same crystal structure .
properties
Amblygonite is very similar to quartz and albite in its optical properties and is therefore often confused with them. A flame test for lithium (if you hold a sample in a gas flame you can see a bright red flame), its density and its unusual cleavability, you can distinguish it from the others.
Education and Locations
Amblygonite is mainly formed in igneous rocks and is therefore mainly found in lithium pegmatites together with spodumene , lepidolite or zinnwaldite or in phosphate pegmatites together with apatites , triphyline or monazite . Often there are also associations with ore minerals such as cassiterite and tantalite (Mn) . Amblygonite is seldom formed from hydrothermal solutions in old or dike deposits .
Locations include Laghman in Afghanistan ; Cordoba in Argentina ; New South Wales and Western Australia in Australia ; Minas Gerais and São Paulo in Brazil ; Henan and Jiangxi in the People's Republic of China ; Chemnitz and Ehrenfriedersdorf in Germany ; Viitaniemi in Finland ; Manitoba and Nova Scotia in Canada ; Sud-Kivu in the Democratic Republic of the Congo ; Mogok in Myanmar ; Utö in Sweden ; Bohemia , Moravia and Vernéřov in the Czech Republic ; and Black Hills (South Dakota) in the USA . Huge, massive aggregates weighing up to 200 tons were also discovered in Keystone (also in South Dakota).
use
As a raw material
Amblygonite is an important ore for the extraction of lithium , but it is also used as a raw material in the ceramic industry.
As a gem
Amblygonite is one of the lesser known gem stones . However, clear varieties, cut in a facet shape, can look confusingly similar to the more valuable “gemstones” golden beryl , citrine and others. Other possibilities of confusion exist with apatite , brazilianite and the green to yellowish-green spodumene variety hiddenite .
See also
literature
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 158
- 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 , p. 251: Pegmatite as a raw material carrier
- Paul Ramdohr , Hugo Strunz : Textbook of Mineralogy . 16th edition. Ferdinand Enke Verlag, 1978, ISBN 3-432-82986-8 , pp. 627-628
Web links
- Mineral Atlas: Amblygonite (Wiki)
Individual evidence
- ↑ a b c d e f g h i Amblygonite at mindat.org (English)
- ↑ Amblygonites . Webmineral (English)
- ↑ Stefan Weiß: The large Lapis mineral directory . 4th edition. Christian Weise Verlag, Munich 2002, ISBN 3-921656-17-6
- ^ New Dana Classification of Anhydrous Phosphates, etc. Containing Hydroxyl or Halogen . Web mineral
- ↑ Localities for Amblygonite . MinDat (English)
- ^ Walter Schumann: Precious stones and gemstones . 13th edition. BLV, Munich 2002, ISBN 3-405-16332-3 , p. 208