Manganese vesuvianite
| Manganese vesuvianite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 2000-040 |
| chemical formula | Ca 19 (Al, Mg, Fe 2+ ) 13 (SiO 4 ) 10 (Si 2 O 7 ) 4 O (F, OH) 9 |
|
Mineral class (and possibly department) |
Silicates and Germanates |
|
System no. to Strunz and to Dana |
9.BG.35 ( 8th edition : VIII / C.26) 0258-04-04 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | tetragonal-dipyramidal 4 / m |
| Space group | P 4 / n |
| Lattice parameters | a = 15.575 Å ; c = 11.824 Å |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 6 to 7 |
| Density (g / cm 3 ) | 3.404 |
| Cleavage | no |
| Break ; Tenacity | shell-like, brittle |
| colour | red, red-brown, black |
| Line color | reddish white |
| transparency | transparent to opaque |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n ω = 1.735 n ε = 1.724 |
| Birefringence | δ = 0.012 |
| Optical character | uniaxial negative |
Manganese vesuvianite is a very rarely occurring mineral from the mineral class of " silicates and germanates ". It crystallizes in the tetragonal crystal system with the chemical composition Ca 19 (Al, Mg, Fe 2+ ) 13 (SiO 4 ) 10 (Si 2 O 7 ) 4 O (F, OH) 9 and is found in the form of thin, prismatic crystals of a few millimeters to a few centimeters in length and red, red-brown or black in color.
Etymology and history
The mineral was named because of its close relationship with Vesuvianite , but with the difference in the chemical composition of the excess manganese .
Manganese vesuvianite was first discovered in 2000 in the “Wessels Mine” near Hotazel in the South African Kalahari and described by T. Armbruster, E. Gnos., R. Dixon, J. Gutzmer, C. Hejny, N. Döbelin and O. Medenbach.
classification
In the meanwhile outdated system of minerals according to Strunz (8th edition) , manganese vesuvianite still belongs to the general division of " group silicates (sorosilicates)", where it forms a separate group together with fluorous vesuvianite , vesuvianite and Wiluit .
Since the revision of Strunz's mineral systematics in the 9th edition , this section has also been more precisely subdivided according to the type of silicate complexes occurring in the compound and the coordination of the cations involved . The manganese vesuvianite is accordingly together with the vesuvianite group unchanged in the assigned minerals in the new subdivision of the “group silicates with mixed SiO 4 and Si 2 O 7 groups; Cations in octahedral [6] and greater coordination ”.
The systematics of minerals according to Dana , which is common in the English-speaking world , also assigns manganese vesuvianite to the group silicates department, but there in the subdivision of “group silicates with insular, mixed, individual and larger tetrahedral groups and cations in [6] and higher coordination; Single and double groups (n = 1.2) ”, where it also forms its own group, the Vesuvianite group, together with fluorosuvianite, vesuvianite and wiluit .
Education and Locations
Manganese vesuvianite is formed by hydrothermal processes from primary manganese ore veins and drusen .
Apart from its type locality , the “Wessels Mine” in South Africa , the mineral could only be detected in the “Harstigen Mine” near Pajsberg / Filipstad in Sweden (as of 2009).
Crystal structure
Manganese vesuvianite crystallizes in the tetragonal crystal system in the space group P 4 / n with the lattice parameters a = 15.575 Å and c = 11.824 Å as well as two formula units per unit cell .
See also
Individual evidence
- ↑ a b c Webmineral - Manganese Vesuvianite (English)
- ↑ a b American Mineralogist Crystal Structure Database - Manganese vesuvianite (English, 2003)
- ↑ a b c d e Manganese vesuvianites at mindat.org (engl.)
- ↑ IMA / CNMNC List of Mineral Names - Manganese Vesuvianite (English, PDF 1.8 MB)
- ↑ American Mineralogist Crystal Structure Database - Manganese Vesuvianite (English, 2003)