Rostite
| Rostite | |
|---|---|
 (size 5 cm × 3.5 cm × 3 cm) |
|
| General and classification | |
| other names |
|
| chemical formula | Al [OH | SO 4 ] • 5H 2 O |
|
Mineral class (and possibly department) |
Sulfates and relatives |
|
System no. to Strunz and to Dana |
7.DB.10 ( 8th edition : VI / D.06) 09/31/11/02 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | orthorhombic-dipyramidal; 2 / m 2 / m 2 / m |
| Space group | Pcab (No. 61, position 2) |
| Lattice parameters | a = 11.17 Å ; b = 13.04 Å; c = 10.87 Å |
| Formula units | Z = 8 |
| Physical Properties | |
| Mohs hardness | "soft" |
| Density (g / cm 3 ) | measured: 1.892; calculated: 1.92 to 1.96 |
| Cleavage | Please complete |
| colour | white, colorless, light blue |
| Line color | White |
| transparency | translucent |
| shine | Please complete |
| Crystal optics | |
| Refractive indices |
n α = 1.461 n β = 1.470 n γ = 1.484 |
| Birefringence | δ = 0.023 |
| Optical character | biaxial positive |
Rostite is a very rare mineral from the mineral class of " sulfates ( and relatives )". It crystallizes in the orthorhombic crystal system with the chemical composition Al [OH | SO 4 ] · 5H 2 O and develops mostly kidney or earthy to massive mineral aggregates , but also flattened rhombohedral or tabular crystals up to about 0.5 mm in size of predominantly white color and white line color . Colorless or light blue rostites are also known.
Etymology and history
The mineral was first discovered in the "Kladno Mine" near Libušín in the Czech Republic and described in 1937 by Rudolph Rost (1902-) under the name Lapparentit , who specified Al [OH | SO 4 ] · 5H 2 O as the chemical formula .
In 1973 P. Bariand, Berthelon, Cesbron and Sadrzadeh described an orthorhombic crystallizing mineral from the type locality Kavir-e-Sagand in the Iranian province of Yazd with apparently the same composition as Rost's lapparentite, which they called khademite . A chemical analysis to determine a possible fluorine content was not carried out due to the small amount of sample.
In 1979 F. Čech also described a chemically identical mineral, but with a slightly smaller unit cell . With recognition by the CNMNC, he gave the mineral the name Rostit in honor of its first describer Rudolph Rost. The method proposed by P. Bariand et al. The khademite described was then regarded as a synonym for the rostite.
B. Bachet, FP Cesbron and R. Chevalier were finally able to resolve the crystal structure of the mineral from Iran in 1981 and also found that the smaller atomic position requires the presence of fluorine and makes it impossible to occupy it with OH anions. The chemical formula of khademite was therefore redefined with Al [F | SO 4 ] · 5H 2 O and secured by Williams and Cesbron with material from the "Lone Pine Mine" ( Catron County , New Mexico, USA).
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the rostite belonged to the mineral class of "sulfates, selenates, tellurates, chromates, molybdates, wolframates" and there to the department of "hydrous sulfates with foreign anions ", where it belongs together with alumite , Felsőbányait , Hydrobasaluminit , Jurbanite , Khademit , meta Aluminite and Zaherite formed a distinct group.
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the IMA, also assigns the rostite to the class of "sulfates (selenates, tellurates, chromates, molybdates and tungstates)" and then to the department of "sulfates (selenates, etc.)" .) with additional anions, with H 2 O “. However, this section is more precisely subdivided according to the size of the cations involved and the crystal structure, so that the mineral is classified according to its composition in the sub-section “with medium-sized cations; isolated octahedra and limited units ”, where it forms the unnamed group 7.DB.10 only together with khademit .
The systematics of minerals according to Dana assigns the rostite to the class of "sulfates, chromates and molybdates" and there in the department of "hydrated sulfates with hydroxyl or halogen". Here it can also be found together with khademite in the unnamed group 09/31/11 within the subdivision of " Hydrogen sulfates with hydroxyl or halogen with (A + B 2+ ) (XO 4 ) Z q × x (H 2 O) ".
Crystal structure
Rostite crystallizes orthorhombically in the space group Pcab (space group no. 61, position 2) with the lattice parameters a = 11.17 Å ; b = 13.04 Å and c = 10.87 Å and 8 formula units per unit cell .
Modifications and varieties
The compound Al [OH | SO 4 ] · 5H 2 O is dimorphic and occurs in nature as monoclinic jurbanite in addition to the orthorhombically crystallizing rostite .
Education and Locations
Rostite usually forms in burning heaps by splitting aluminum-containing rocks into sulfur dioxide and fluorine-containing gases. Accompanying minerals include alunogen , copiapit and Tschermigit .
In total, Rostite has been found at five sites so far. In addition to its type locality "Kladno Mine" near Libušín in the Czech Republic, there are also the " Anna Grube " near Alsdorf (North Rhine-Westphalia) in Germany, the "Le Cetine di Cotorniano Mine" near Chiusdino in Tuscany, Italy, the Jagnob River near Kukhi- Malik in Sughd Province in Tajikistan and in the “Nabesna Mine” on the Chisana River in Alaska (USA).
See also
literature
- F. Čech: Rostite, a new name for orthorhombic Al (SO 4 ) (OH) · 5H 2 O , In: New Yearbook for Mineralogy , MONTHS, 1979, pp. 193-196
Web links
- Mineral Atlas: Rostit (Wiki)
Individual evidence
- ↑ a b c d e f 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. 396 .
- ↑ Webmineral - Rostite
- ↑ a b c Rostite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 66.4 kB )
- ↑ Mindat - Rostite
- ↑ a b c Fabien P. Cesbron, Peter Bayliss: Mineralogical notes: mineral nomenclature: khademite , In: Mineralogical Magazine , Volume 52 (1988), pp. 133-134 ( PDF 114.7 kB )
- ↑ Find location list for Rostite in the Mineralienatlas and in Mindat