Bandylite
| Bandylite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Cu [Cl | B (OH) 4 ] |
|
Mineral class (and possibly department) |
Borates (formerly carbonates, nitrates and borates) |
|
System no. to Strunz and to Dana |
6.AC.35 ( 8th edition : V / G.08) 01/25/04/02 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | tetragonal-dipyramidal; 4 / n |
| Room group (no.) | P 4 / n (No. 85) |
| Lattice parameters | a = 6.17 Å ; c = 5.59 Å |
| Formula units | Z = 2 |
| Frequent crystal faces | {001}, {111}, {201}, {110} |
| Physical Properties | |
| Mohs hardness | 2.5 |
| Density (g / cm 3 ) | measured: 2.810; calculated: 2.81 |
| Cleavage | completely after {001} |
| Break ; Tenacity | Split leaves flexible |
| colour | dark blue to greenish |
| Line color | Light Blue |
| transparency | transparent to translucent |
| shine | Glass gloss, pearlescent, matt |
| Crystal optics | |
| Refractive indices |
n ω = 1.691 to 1.692 n ε = 1.640 to 1.641 |
| Birefringence | δ = 0.051 |
| Optical character | uniaxial negative |
| Pleochroism | strong: O = dark blue; E = light greenish yellow |
| Other properties | |
| Chemical behavior | water soluble |
Bandylite is a very rarely occurring mineral from the mineral class of " borates " (formerly carbonates, nitrates and borates, see classification ). It crystallizes in the tetragonal crystal system with the chemical composition Cu [Cl | B (OH) 4 ], and is thus chemically seen a basic copper borate with additional chlorine - ions .
Bandylite is transparent to translucent and develops only small, tabular or pyramidal crystals of a few millimeters in size, which are usually arranged in radial groups or fused to form lichen-like aggregates. Its color varies from dark blue and greenish blue, with the greenish hue is the stronger, the more Atacamit - inclusions it contains. Undamaged and unweathered crystal surfaces have a glass-like sheen , whereas the cleavage surfaces have a more mother-of-pearl shimmer .
Special properties
Bandylite is completely cleavable perpendicular to the c-axis. Thin split leaves are very flexible and easily deformable. The mineral decomposes in water and in the air it weathers over time to eriochalcite .
Etymology and history
Bandylith was first discovered in 1935 in the "Queténa Mine" near Chuquicamata in the Atacama Desert in northern Chile and described in 1938 by Charles Palache and William F. Foshag, who named the mineral after its discoverer, Mark Chance Bandy .
classification
In the meantime outdated, but still in use 8th edition of the mineral classification by Strunz of Bandylith belonged to common mineral class of "carbonates, nitrates and borates" and then to the Department of "Island borates" where he along with Cahnit and Teepleit the "Bandylith-Cahnit -Group "with the system no. V / G.08 formed.
The 9th edition of Strunz's mineral systematics, which has been in force since 2001 and is used by the International Mineralogical Association (IMA), assigns the bandylite to the newly defined class of "borates" and there into the department of "monoborates". This is further subdivided according to the structure of the borate complex and the possible presence of additional anions , so that the mineral is classified according to its composition in the subsection “B (O, OH) 4 , with and without additional anions; 1 (T), 1 (T) + OH etc. ”can be found where it is the only member of the unnamed group 6.AC.35 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the bandylite, like the outdated Strunz system, to the common class of “carbonates, nitrates and borates” and there to the division and subdivision of the same name of “ anhydrous borates with hydroxyl or halogen " a. Here you can find him together with Teepleit in the unnamed group 01/25/04 .
Education and Locations
Bandylite forms secondarily in the leaching zone above massive iron sulfates. As Begleitminerale can still beside Atacamit and the weathering product Eriochalcit among other Starkeyit occur.
In addition to its type locality "Queténa Mine", so far (as of 2013) only the area around the port city of Taltal, which is also in the Región de Antofagasta in northern Chile, is known as a site.
Crystal structure
Bandylith crystallizes tetragonally in the space group P 4 / n (space group no. 85) with the lattice parameters a = 6.17 Å and c = 5.59 Å as well as two formula units per unit cell .
See also
literature
- C. Palache, WF Palache: Antofagastite and bandylite, two new copper minerals from Chile , In: American Mineralogist , Volume 23 (1938), pp. 85–90 ( PDF 361 kB )
Web links
- Mineral Atlas: Bandylite (Wiki)
- Web mineral - Bandylite
- Database-of-Raman-spectroscopy - Bandylite
- American-Mineralogist-Crystal-Structure-Database - Bandylite
Individual evidence
- ↑ a b c d e 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. 336 .
- ↑ a b c d Bandylite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 68.4 kB )
- ↑ Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 727 .
- ↑ a b Mindat - Bandylite