Sodium dufrénite
| Sodium dufrénite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1981-033 |
| chemical formula | NaFe 2+ Fe 3+ 5 [(OH) 6 | (PO 4 ) 4 ] • 2H 2 O |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.DK.15 ( 8th edition : VII / D.11) 42.09.01.03 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Room group (no.) | C 2 / c (No. 15) |
| Lattice parameters |
a = 25.83 Å ; b = 5.15 Å; c = 13.77 Å β = 111.5 ° |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 3 to 4 |
| Density (g / cm 3 ) | measured: 3.20 (5); calculated: 3.23 |
| Cleavage | Please complete |
| colour | blue-green, greenish-brown, greenish-black |
| Line color | green |
| transparency | translucent |
| shine | Please complete |
| Crystal optics | |
| Refractive indices |
n α = 1.756 n γ = 1.775 |
| Birefringence | δ = 0.019 |
| Optical character | biaxial positive |
Natrodufrénit is a rarely occurring mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the monoclinic crystal system with the chemical composition NaFe 2+ Fe 3+ 5 [(OH) 6 | (PO 4 ) 4 ] · 2H 2 O, is thus a hydrous sodium - iron phosphate with additional hydroxide .
Natrodufrénit usually develops compact, spherulitic to radial-rayed mineral aggregates from fibrous crystals up to about five millimeters in diameter and blue-green or greenish-brown to greenish-black in color.
Etymology and history
The mineral was first discovered in 1910 by Antoine Lacroix in the French municipality of Rochefort-en-Terre (Bretagne), who, however, mistakenly used it for the already known Dufrénite (Ca 0.5 Fe 2+ Fe 3+ 5 [(OH) 6 | (PO 4 ) 4 ] · 2H 2 O). However, in 1981 F. Fontan, F. Pillard and F. Permingeat discovered when examining the old mineral sample that it contained a predominant proportion of sodium instead of the expected calcium content.
Fontan, Pillard and Permingeate named the new mineral after its relevant sodium content and its relationship with dufrénit as natrodufrénite and submitted their results for examination to the International Mineralogical Association (IMA) (register no.IMA 1981-033 ), which still has natrodufrénit recognized as a separate mineral in the same year.
Type material of the mineral is kept in the Muséum national d'histoire naturelle (register no. 106384, 106385) and in the Mines ParisTech ( École nationale supérieure des mines , register no. 18329) in Paris .
classification
In the meantime outdated, but still in use 8th edition of the mineral classification by Strunz of Natrodufrénit belonged to the department of "water containing phosphates with foreign anions " where he along with Beraunit , Bermanit , Burangait , Dufrénit , Ercitit , Ferristrunzit , Ferrostrunzit , Gormanit , Kakoxen , Kidwellit , Laubmannit , Matioliit , Meurigit-K , Meurigit-Na , Oxiberaunit , Souzalith , Strunzit and Tinticit the "Strunzit-Beraunit-Gruppe" with the system no. VII / D.11 formed.
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 the natrodufrénite to the category of “phosphates etc. with additional anions; with H 2 O “. However, this is further subdivided according to the relative size of the cations involved and the molar ratio of the additional anions to the phosphate, arsenate or vanadate complex (RO 4 ), so that the mineral is classified in the sub-section “With large and medium-sized cations; (OH etc.): RO 4 > 1: 1 and <2: 1 "can be found, where together with Burangait, Dufrénit, Gayit and Matioliit the" Dufrénite group "with the system no. 8.DK.15 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns natrodufrénite to the class of “phosphates, arsenates and vanadates” and there in the category of “water-containing phosphates etc., with hydroxyl or halogen”. Here he is together with Burangait, Dufrénit, Gayit and Matioliit in the "Burangaitgruppe" with the system no. 42.09.01 within the sub-section " Water-containing phosphates etc., with hydroxyl or halogen with (A) 3 (XO 4 ) 2 Z q × x (H 2 O) ".
Education and Locations
Sodium dufrénite forms secondarily at low temperatures in sinking and weathering limonite veins, where it usually occurs in paragenesis with cyrilovite and goethite .
As a rare mineral formation, soda dufrénite could only be detected at a few sites, whereby so far (as of 2013) around 30 sites are known. In addition to its type locality Rochefort-en-Terre, the mineral was found in France in the "La Lande" quarry near Plumelin in Brittany, near Échassières in the Allier department in Auvergne and in the "Puech de Leguo" quarry near La Capelle-Bleys in the department Aveyron in Midi-Pyrénées.
In Germany, natrodufrénite is known so far only from the Althollert mine ( Hollertszug ) near Dermbach (Herdorf) in Rhineland-Palatinate and from the Greifenstein near Ehrenfriedersdorf in Saxony.
The only previously known site in Austria is Eichberg in the market town of Großdietmanns in Lower Austria.
Other previously known sites are in Argentina, Australia, Chile, Italy, Morocco, Portugal, Spain, the Czech Republic and in the US state of Arizona.
Crystal structure
Natrodufrénite crystallizes monoclinically in the space group C 2 / c (space group no. 15) with the lattice parameters a = 25.83 Å ; b = 5.15 Å; c = 13.77 Å and β = 111.5 ° and 4 formula units per unit cell .
See also
literature
- F. Fontan, F. Pillard, F. Permingeate: La natrodufrénite (Na, □) (Fe +++ , Fe ++ ) (F e +++ , Al) 5 (PO 4 ) 4 (OH) 6 · 2H 2 O, une nouvelle espèce minérale du groupe de la dufrénite , In: Bulletin de Minéralogie , Volume 105 (1982), pp. 321-326
- PJ Dunn, JD Grice, M. Fleischer, A. Pabst: New mineral names , In: American Mineralogist , Volume 68 (1983), pp. 1038-1041 ( PDF 715 kB ; p. 2)
Web links
Individual evidence
- ↑ a b c d e 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. 515 .
- ↑ Webmineral - Natrodufrénite
- ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 5th completely revised and supplemented edition. Weise, Munich 2008, ISBN 978-3-921656-70-9 .
- ↑ Natrodufrénite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 65.6 kB )
- ↑ a b Mindat - Natrodufrénite
- ↑ Mindat - Number of localities for Natrodufrénite
- ↑ Find location list for Natrodufrénite in the Mineralienatlas and Mindat