Fluorvesuvianite
| Fluorvesuvianite | |
|---|---|
| General and classification | |
| 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) 0258-04-03 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | ditetragonal-dipyramidal 4 / m 2 / m 2 / m |
| Space group | P 4 / nnc |
| Lattice parameters | a = 15.5295 Å ; c = 11.78084 Å |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 6th |
| Density (g / cm 3 ) | 3.43 |
| Cleavage | no |
| Break ; Tenacity | brittle |
| colour | colorless, silky white |
| Line color | White |
| transparency | transparent |
| shine | Glass gloss, silk gloss |
Fluorvesuvianite is a 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 needle-like to fibrous crystals or radial radial mineral aggregates up to 1.5 mm in size.
Larger crystals are colorless with glass-shining crystal surfaces. In the case of fibrous formation, however, fluorvesuvianite appears white and has a satin gloss due to the light scattering.
Etymology and history
The mineral was named because of its close relationship with Vesuvianite , albeit with the difference in the chemical composition of the excess fluorine .
classification
In the meanwhile outdated system of minerals according to Strunz (8th edition) , the fluorous vesuvianite still belongs to the general division of " group silicates (sorosilicates)", where it forms a separate group together with manganese 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 fluorous vesuvianite is accordingly together with the vesuvianite group unchanged in the assigned minerals in the new subdivision of “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 fluorine vesuvianite to the group of silicates, but there in the subdivision of “group silicates with insular, mixed, single 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 manganese vesuvianite, vesuvianite and Wiluit .
Education and Locations
No further details can yet be given about the exact formation conditions, since the mineral has so far only been proven at its type locality , the "Lupikko Mine" near Pitkjaranta in the Russian Republic of Karelia . It appeared there in calcitangereicherten Druze of occurring in the area diopside - magnetite - skarn on.
Crystal structure
Fluorosuvianite crystallizes in the tetragonal crystal system in the space group P 4 / nnc with the lattice parameters a = 15.5295 Å and c = 11.78084 Å as well as two formula units per unit cell .
See also
Individual evidence
- ↑ a b c Webmineral - Fluorvesuvian (English)
- ↑ a b American Mineralogist Crystal Structure Database - Fluorvesuvianite (English, 2003)
- ↑ a b Fluorvesuvianite at mindat.org (engl.)
- ↑ IMA / CNMNC List of Mineral Names - Fluorvesuvianite (English; PDF 1.8 MB; p. 99)
- ↑ American Mineralogist Crystal Structure Database - Fluorvesuvianite (English, 2003)