Lazurite
| Lazurite | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula |
|
|
Mineral class (and possibly department) |
Silicates and Germanates |
|
System no. to Strunz and to Dana |
9.FB.10 ( 8th edition : VIII / J.11) 76.02.03.04 |
| Crystallographic Data | |
| Crystal system | cubic |
| Crystal class ; symbol | cubic-hexakistrahedral; 4 3 m |
| Space group | see crystal structure |
| Lattice parameters | see crystal structure |
| Formula units | see crystal structure |
| Physical Properties | |
| Mohs hardness | 5.5 |
| Density (g / cm 3 ) | measured: 2.38 to 2.45; calculated: 2.39 to 2.42 |
| Cleavage | imperfect after {110} |
| Break ; Tenacity | uneven, brittle |
| colour | blue, azure blue, violet blue to green blue |
| Line color | blue |
| transparency | translucent to opaque |
| shine | Glass gloss, matt |
| Crystal optics | |
| Refractive index | n = 1.502 to 1.522 |
| Birefringence | none, as isometric |
Lasurite is a seldom occurring mineral from the mineral class of " silicates and germanates " with the idealized chemical composition Na 3 Ca (Si 3 Al 3 ) O 12 S and therefore, chemically speaking, a sodium - calcium - aluminosilicate with additional sulfur ions .
Lasurite predominantly crystallizes in the cubic crystal system . Known, albeit rarely, are orthorhombic or triclinic lazurites (see crystal structure ).
Lasurite is found in particular as a component of lapis lazuli , but also occurs in pure form as dodecahedral and, more rarely, cubic crystals or as granular to massive and ingrown mineral aggregates .
Etymology and history
Lasurite was discovered in the Ladjuar Medam lapis lazuli deposit near Sar-e-Sang in the Kuran va Munjan district (Badachschan province) in Afghanistan and was first scientifically described in 1890 by Waldemar Christofer Brøgger and H. Bäckström. They named the mineral based on its color after the Persian wordلاژورد/ lāžward for blue or " sky blue ".
The Georgian prince Vaxushti Batonishvili (Wakushti Batonishvili , 1696–1757) described in his historical chronicle Das Leben Kartlis a mining area in southeast Georgia south of the city of Bolnissi that had existed since the Early Bronze Age , where iron, copper and lazurite were processed in his time.
classification
In the meantime outdated, but still in use 8th edition of the mineral classification by Strunz of Lasurit belonged to the mineral class of "silicates and Germanates" and there to the general ward of the " framework silicates (tectosilicates)" where he collaborated with Bicchulith , hauyne , Kamaishilith , Nosean , Sodalith , Tsaregorodtsevit and Tugtupit the independent "sodalite group" with the system no. VIII / J.11 formed.
Since 2001, fixed by the International Mineralogical Association used (IMA) 9th edition of Strunz'schen systematic mineral also assigns the Lasurit in the class of "silicates and Germanates", but there into the already finely subdivided department of the " framework silicates (tectosilicates) without zeolitic H 2 O “. This section is further subdivided according to the possible presence of further anions in the formula, so that the mineral can be found in the sub-section "Tectosilicates (tectosilicates) with additional anions" according to its composition, where it can be found together with Bicchulite, Danalith , Genthelvin , Haüyn , Helvin, Kamaishilith, Nosean, Sodalith, Tsaregorodtsevit and Tugtupit the "Sodalite-Danalith Group" with the system no. 9.FB.10 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the lazurite to the class of "silicates and germanates", but there it is in the category of "structural silicates: Al-Si lattice". Here he is also a member of the "sodalite group" with the system no. 76.02.03 within the sub-section “ Framework silicates: Al-Si lattices, feldspar representatives and related species ”.
Crystal structure
Lasurit comes in three modifications of different crystal structure before, wherein the cubic modification Lasurit-1C is the most common form of training and in the space group P 4 3 n (space group no. 218) with the lattice parameter a = 9.10 Å , as well as a formula unit per unit cell crystallized .
The other two polymorphs are:
- Lasurit-6O : Orthorhombic in the space group Pnna (space group no. 52) with the lattice parameters a = 9.07 Å ; b = 12.83 Å and c = 38.49 Å as well as 6 formula units per unit cell .
- Lasurit-4A : Triclinic in space group P 1 (space group no. 1) with the lattice parameters a = 9.07 Å ; b = 12.90 Å; c = 25.71 Å; α = 90.0 °; β = 90.1 ° and γ = 90.2 ° as well as 4 formula units per unit cell .
Education and Locations
Lasurit formed by contact metamorphism in limestone , where he next calcite among others still with diopside , forsterite , hauyne , Humit , muscovite and pyrite associated can be found.
As a rare mineral formation, lazurite has so far (as of 2011) only been detected at fewer than 50 sites. In addition to its type locality Ladjuar Medam, the mineral occurred in Afghanistan in other places in the province of Badachschan and in the province of Panjshir .
Other locations are in Chile, Canada, Italy, Myanmar, Russia, Sweden, Slovakia, Tajikistan and in various states of the United States of America.
literature
- WC Brögger, H. Bäckström: The minerals of the garnet group , in P. Groth (Hrsg.): Zeitschrift für Krystallographie und Mineralogie , Volume 18, Leipzig 1891, pp. 209–276 ( PDF 4.3 MB )
- Paul Ramdohr , Hugo Strunz : Klockmann's textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, Stuttgart 1978, ISBN 3-432-82986-8 , p. 786 .
- Martin Okrusch, Siegfried Matthes: Mineralogy. An introduction to special mineralogy, petrology and geology . 7th fully revised and updated edition. Springer Verlag, Berlin et al. 2005, ISBN 3-540-23812-3 , pp. 125 .
- Henri Brasseur: Sur les structures de l'azurite et de la malachite , Brussels, Hayez, 1933; also Liège (dissertation)
Web links
- Mineralienatlas: Lasurit und Mineralienatlas: Mineralienportrait / Lasurit (Wiki)
- Database-of-Raman-spectroscopy - Lazurite
- Education server for chemistry - Uni Bielefeld
See also
Individual evidence
- ↑ a b Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: July 2019. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, July 2019, accessed September 9, 2019 .
- ↑ a b c d Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 699 .
- ↑ David Barthelmy: Lazurite MineralData. In: webmineral.com. Retrieved September 9, 2019 .
- ↑ Lazurite . 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; 71 kB ; accessed on September 9, 2019]).
- ↑ a b c Lazurite. In: mindat.org. Hudson Institute of Mineralogy, accessed September 9, 2019 .
- ↑ Thomas Stöllner , Irina Gambaschidze, Andreas Hauptmann, Giorgi Mindiašvili, Giorgi Gogočuri, Gero Steffens: Gold Mining in Southeast Georgia - New Research on Early Bronze Age Mining in Georgia. German Mining Museum Bochum on bergbaumuseum.de, p. 5
- ↑ Localities for Lazurite. In: mindat.org. Hudson Institute of Mineralogy, accessed September 9, 2019 .