Vauxite
| Vauxite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Fe 2+ Al 2 [OH | PO 4 ] 2 • 6 H 2 O |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.DC.35 ( 8th edition : VII / D.09) 11.42.14.01 |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triclinic-pinacoidal 1 |
| Space group | P 1 |
| Lattice parameters |
a = 9.13 Å ; b = 11.59 Å; c = 6.14 Å, α = 98.3 °; β = 92.0 °; γ = 108.4 ° |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 3.5 |
| Density (g / cm 3 ) | 2.39 to 2.40 |
| Cleavage | no |
| Break ; Tenacity | brittle |
| colour | sky blue, teal |
| Line color | White |
| transparency | transparent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.551 n β = 1.555 n γ = 1.562 |
| Birefringence | δ = 0.011 |
| Optical character | biaxial positive |
| Axis angle | 2V = 32 ° |
Vauxite is a very rarely occurring mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the triclinic crystal system with the chemical composition of Fe 2+ Al 2 [OH | PO 4 ] 2 • 6 H 2 O and developed mostly larger, partially radialstrahlige mineral aggregates consisting of many tabular up prismatic single crystals of sky blue to blue-green color .
Etymology and history
The mineral was named after George Vaux , Jr. (1863-1927), a US lawyer and mineral collector.
It was first found in 1922 in the "Siglo Veinte Mine (Llallagua Mine)" near Llallagua in Bolivia and described by Samuel George Gordon (1897-1953), who also described metavauxite and paravauxite as another new mineral from this site .
classification
In the old (8th edition) and new systematics of minerals (9th edition) according to Strunz , the vauxite belongs to the division of "water-containing phosphates with foreign anions ". Since the new Strunz mineral classification, however, this department has also been more precisely subdivided according to the size of the cations and the ratio of hydroxyl group to cation complex and the mineral is now in the subdivision “With only medium-sized cations; (OH etc.): RO 4 = 1: 1 and <2: 1 “.
The systematics of minerals according to Dana , which is common in the English-speaking world , assigns vauxite to the division of " hydrated phosphates etc., with hydroxyl or halogen with (AB) 4 (XO 4 ) 3 Z q • x (H 2 O) ", where it , together with Paravauxit Sigloit , Gordonit , Mangangordonit and Kastningit forms the unnamed group "42.11.14".
Education and Locations
Vauxite is a secondary mineral that is formed from apatite through weathering . Accompanying minerals include wavellite , paravauxite and marcasite .
So far, the mineral could only be detected in Bolivia , on the one hand at its type locality "Siglo Veinte Mine (Llallagua Mine)" near Llallagua in Potosí and on the other hand near Huanuni in Oruro.
Crystal structure
Vauxite crystallizes triclinically in the space group with the lattice parameters a = 9.13 Å ; b = 11.59 Å; c = 6.14 Å; α = 98.3 °; β = 92.0 ° and γ = 108.4 ° as well as two formula units per unit cell .
See also
Individual evidence
- ↑ a b c Webmineral - Vauxite (English)
- ↑ a b American Mineralogist Crystal Structure Database - Vauxite (English, 1968)
- ↑ a b c d Vauxite at mindat.org (engl.)
- ^ 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. 501 .
- ↑ JSTOR - Vauxite and Paravauxite, two new minerals from Llallagua, Bolivia by Samuel G. Gordon (English)
- ↑ Memorial of Samuel George Gordon (English, PDF 542.7 kB)
- ↑ American Mineralogist Crystal Structure Database - Vauxite (English, 1968)
literature
- Paul Ramdohr , Hugo Strunz : Klockmann's textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, 1978, ISBN 3-432-82986-8 , pp. 648 .
Web links
- Mineral Atlas: Vauxite (Wiki)
- Handbook of Mineralogy - Vauxite (English, PDF 64.8 kB)