Pretulite

from Wikipedia, the free encyclopedia
Pretulite
General and classification
other names

IMA 1996-024

chemical formula Sc [PO 4 ]
Mineral class
(and possibly department) 		Phosphates, arsenates and vanadates
System no. to Strunz
and to Dana 		8.AD.35 ( 8th edition : VII / A.14)
04/38/11/05
Crystallographic Data
Crystal system tetragonal
Crystal class ; symbol ditetragonal-dipyramidal; 4 / m  2 / m  2 / m
Space group I 4 1 / amd (No. 141)Template: room group / 141
Lattice parameters a  = 6.59  Å ; c  = 5.81 Å
Formula units Z  = 4
Frequent crystal faces {211}, {100}, {111}
Physical Properties
Mohs hardness 5
Density (g / cm 3 ) calculated: 3.71
Cleavage completely after {100}
Break ; Tenacity splintery; brittle
colour white, pink, light to dark orange
Line color White
transparency transparent to translucent
shine Diamond luster
Crystal optics
Refractive indices n ω  = 1.790
n ε  = 1.860
Birefringence δ = 0.070
Optical character uniaxial positive
Other properties
Special features weak orange fluorescence under short-wave UV light; blue cathodoluminescence

Pretulit is a rarely occurring minerals from the mineral class of "phosphates, arsenates, and vanadates" with the chemical composition Sc [PO 4 ] and chemical point of view, a scandium - phosphate .

Pretulite crystallizes in the tetragonal crystal system and develops small, dipyramidal crystals or irregular grains up to about 200  μm in diameter with a diamond-like sheen on the surfaces. In its pure form, pretulite is colorless and transparent. However, due to multiple light refraction due to lattice construction defects or polycrystalline training, it can also be translucent white and, due to foreign admixtures, take on a pink or light to dark orange color.

Etymology and history

Pretulite was first discovered on the Pretulalpe near Fürstenbauer in the Fischbacher Alps in the Austrian state of Styria . It was first described in 1998 by Franz Bernhard, Franz Walter, Karl Ettinger, Josef Taucher and Kurt Mereiter, who named the mineral after its first place of discovery. However , the Höllkogel, 100 meters to the northeast, is considered to be the type locality , as the best samples for a complete analysis of the mineral were found in its rock.

The type material of the mineral is kept in the Landesmuseum Joanneum in Graz and in the Natural History Museum Vienna in Austria as well as in the mineralogical collection of the TU Bergakademie Freiberg (catalog no. 78912 / c 7.5).

classification

In the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the pretulite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "anhydrous phosphates [PO 4 ] 3− , without foreign anions ", where it together with Chernovit- (Y) , Wakefieldit- (Ce) , Wakefieldit- (La) , Wakefieldit- (Y) , Xenotime- (Y) and Xenotime- (Yb) the "Xenotime group" with the system no. VII / A.14 .

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns pretulite to the category of “phosphates etc. without additional anions; without H 2 O “. However, this is further subdivided according to the relative size of the cations involved , so that the mineral can be found according to its composition in the subsection “With only large cations”, where it is also found together with Chernovite- (Y), Dreyerite, Wakefieldite- (Ce ), Wakefieldit- (La), Wakefieldit- (Nd), Wakefieldit- (Y), Xenotim- (Y) and Xenotim- (Yb) the "Xenotime group" with the system no. 8.AD.35 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns pretulite to the class of "phosphates, arsenates and vanadates" and there in the department of "anhydrous phosphates etc.". Here it is also in the " Xenotime group (tetragonal: I 4 1 / amd ) " with the system no. 38.04.11 can be found in the subsection “Anhydrous phosphates etc., A + XO 4 ”.

Crystal structure

Pretulite crystallizes tetragonally in the space group I 4 1 / amd (space group no. 141) with the lattice parameters a  = 6.59  Å and c  = 5.81 Å and 4 formula units per unit cell . Template: room group / 141

properties

Under UV light , pretulite shows only a weak orange fluorescence , while under cathode rays it shows a strong, blue cathodoluminescence .

Education and Locations

Pretulit formed in Lazulith - quartz - veins within phyllite - mica schists . In addition to the minerals already mentioned, augelite , bearthite , chlorapatite , florencite (Ce) , fluorapatite , goyazite , hydroxyl herderite , clinochlor , corundum , muscovite , paragonite , rutile , wardite and xenotime (Y) can also occur as accompanying minerals .

As a rare mineral formation, pretulite could only be detected at a few localities, although slightly more than 10 localities are known to date (as of 2014). In addition to its type locality Höllkogel and the Pretulalpe near Fürstenbauer, the mineral also appeared in Austria on the Freßnitzkogel, Granegg, Rotriegel and Wegscheidkreuz mountains in the vicinity of Freßnitzgraben- Krieglach and a lazulite discovery site near Traibach ; in the whole valley in the Bruck-Mürzzuschlag district and at Schäffern in the state of Styria.

Furthermore, Pretulit is only known from Dolní Bory in the Czech region of Moravia , the Bois-de-la-Roche quarry in the commune of Saint-Aubin-des-Châteaux in the French Loire-Atlantique department and the Byrud emerald mine near Minnesund in Norway Fylke Akershus .

See also

literature

  • Franz Bernhard, Franz Walter, Karl Ettinger, Josef Taucher, Kurt Mereiter: Pretulite, ScPO 4 , a new scandium mineral from the Styrian and Lower Austrian lazulite occurrences, Austria . In: American Mineralogist . tape 83 , 1998, pp. 625–630 (English, available online at minsocam.org [PDF; 220 kB ; accessed on March 6, 2019]).

Web links

Individual evidence

  1. ↑ Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: November 2018. (PDF 1753 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, November 2018, accessed March 6, 2019 .
  2. ↑ 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 , p.  436 .
  3. ^ David Barthelmy: Pretulite Mineral Data. In: webmineral.com. Retrieved March 6, 2019 .
  4. ↑ a b c d e Pretulite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 64  kB ; accessed on March 6, 2019]).
  5. ↑ a b c Pretulite. In: mindat.org. Hudson Institute of Mineralogy, accessed March 6, 2019 .
  6. ^ Franz Bernhard, Franz Walter, Karl Ettinger, Josef Taucher, Kurt Mereiter: Pretulite, ScPO 4 , a new scandium mineral from the Styrian and Lower Austrian lazulite occurrences, Austria . In: American Mineralogist . tape 83 , 1998, pp. 626 (English, available online at minsocam.org [PDF; 220 kB ; accessed on March 6, 2019]).
  7. ^ Franz Bernhard, Reinhardt Kurtz: Type mineral catalog Germany: Pretulit. In: typmineral.uni-hamburg.de. Mineralogical Museum of the University of Hamburg , December 8, 2017, accessed on March 6, 2019 .
  8. ↑ Localities for Pretulite. In: mindat.org. Hudson Institute of Mineralogy, accessed March 6, 2019 .
  9. ↑ Find location list for pretulite in the Mineralienatlas and in Mindat