Churchit- (Y)
| Churchit- (Y) | |
|---|---|
-102477.jpg) |
|
| General and classification | |
| chemical formula | Y [PO 4 ] • 2H 2 O |
|
Mineral class (and possibly department) |
Phosphates , arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.CJ.50 ( 8th edition : VII / C.25) 04/40/06/01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | A 2 / a (No. 15, position 4) |
| Lattice parameters |
a = 6.27 Å ; b = 15.01 Å; c = 6.15 Å β = 126.6 ° |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 3 |
| Density (g / cm 3 ) | measured: 3.26; calculated: 3.11 |
| Cleavage | perfect according to {001}, good according to {010} and {100} |
| Break ; Tenacity | shell-like |
| colour | colorless to snow-white |
| Line color | White |
| transparency | transparent |
| shine | Glass luster, pearlescent luster on cleavage surfaces |
| Crystal optics | |
| Refractive indices |
n α = 1.605 to 1.623 n β = 1.608 to 1.631 n γ = 1.645 to 1.657 |
| Birefringence | δ = 0.040 |
| Optical character | biaxial positive |
| Axis angle | 2V = 10 ° (measured); 60 ° (calculated) |
Churchite- (Y) (also Weinschenkit or Rogersite ) is a mineral from the class of phosphates , arsenates and vanadates . It crystallizes in the monoclinic crystal system with the chemical composition Y [PO 4 ] · 2H 2 O.
The rare crystals are columnar to needle-like, up to 6 mm long and form radial, often flat aggregates. Churchit- (Y) is colorless to snow-white, rarely also slightly gray or pale flesh-colored with a glass sheen. The density is 3.11-3.26 g / cm 3 and the Mohs hardness is 3.
Etymology and history
The mineral was first described in 1865 by Arthur Herbert Church in samples from Cornwall , England , but with the wrong chemical composition. In 1923, Laubmann described the hydrous Y-phosphate under the name Weinschenkit.
Danas 7th edition of the "System of Mineralogy" (1951) listed the Y-phosphate as Weinschenkit and the Ce-phosphate as Churchit, in honor of the English chemist Arthur Herbert Church. In 1966 the name Churchit- (Y) was introduced for Weinschenkit.
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the Churchit- (Y) belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates without foreign anions ", where it belonged together with brushite , Churchit- (Dy) , Churchit- (Nd) and pharmacolite formed the unnamed group VII / C.25 .
The 9th edition of Strunz's mineral systematics, which has been in force since 2001 and is used by the International Mineralogical Association (IMA), also assigns the Churchit- (Y) to the class of "phosphates, arsenates and vanadates" and there in the department of "phosphates, etc." without additional anions; with H 2 O “. However, this section is further subdivided according to the size of the cations involved , so that the mineral can be found according to its composition in the sub-section “Only with large cations”, where it is unnamed along with ardealite , brushite, Churchite (Nd) and pharmacolite Forms group 8.CJ.50 .
The systematics of minerals according to Dana also assigns Churchit- (Y) to the class of "phosphates, arsenates and vanadates" and there in the department of "water-containing phosphates etc.". Here it can only be found together with Churchit- (Nd) in the unnamed group 04/40/06 within the sub-section “ Water-containing phosphates etc., with A 3+ XO 4 × x (H 2 O) ”.
Crystal structure
Churchit- (Y) crystallizes monoclinically in the same structure type as gypsum in space group A 2 / a (space group no. 15, position 4) with the lattice parameters a = 6.27 Å ; b = 15.01 Å; c = 6.15 Å and β = 126.6 ° as well as 4 formula units per unit cell .
properties
Churchit- (Y) is soluble in hot acids, but insoluble in lye. When carefully heated, Churchit exhibits thermoluminescence .
Education and Locations
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Churchite- (Y) is secondary to the weathering of pegmatites , carbonatites and other Y-containing rocks.
At Mt Weld in Western Australia , Churchit- (Y) occurs along with goyazite , gorceixite , florencite , crandallite , monazite , apatite and cerianite .
The iron ore mines Maffei I and II and Leonie in Auerbach in the Upper Palatinate are well-known sites of the mineral.
From other reserves are assemblages with Rabdophan , Wavellite , turquoises , Variscit , cacoxenite , Beraunit , Dufrénit , Todorokit , Lithiophorit , hematite , limonite and clay minerals described.
See also
literature
- BG Lottermoser: Churchite from the Mt Weld carbonatite laterite, Western Australia . In: Mineralogical Notes . tape 51 , 1986, pp. 468–469 ( minersoc.org [PDF; 502 kB ; accessed on June 16, 2018]).
- Churchite- (Y) . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 68 kB ; accessed on June 16, 2018]).
Web links
- Mineral Atlas: Churchit- (Y) (Wiki)
- RRUFF Database-of-Raman-spectroscopy - Churchite- (Y) (English)
- - Churchite- (Y) (English)
Individual evidence
- ↑ a b c d e Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X .
- ↑ a b c Churchite- (Y) . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 68 kB ; accessed on June 16, 2018]).
- ↑ a b c d e Mindat - Churchite- (Y) (English)