Nealit
| Nealit | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1979-050 |
| chemical formula | Pb 4 Fe 2+ [Cl 4 | (AsO 3 ) 2 ] • 2H 2 O |
|
Mineral class (and possibly department) |
Oxides and hydroxides |
|
System no. to Strunz and to Dana |
4.JD.05 ( 8th edition : IV / J.03) 04.41.06.01 |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triclinic pinacoidal; 1 |
| Space group | P 1 (No. 2) |
| Lattice parameters |
a = 6.55 Å ; b = 10.24 Å; c = 5.59 Å α = 96.2 °; β = 89.6 °; γ = 97.7 ° |
| Formula units | Z = 1 |
| Physical Properties | |
| Mohs hardness | 4th |
| Density (g / cm 3 ) | calculated: 5.88 |
| Cleavage | no |
| Break ; Tenacity | uneven; very brittle |
| colour | yellow to orange |
| Line color | pale orange |
| transparency | transparent |
| shine | Diamond luster |
Nealite is a rarely occurring mineral from the mineral class of "oxides and hydroxides" (including V [5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates). It crystallizes in the triclinic crystal system with the chemical composition Pb 4 Fe 2+ [Cl 4 | (AsO 3 ) 2 ] · 2H 2 O and is therefore chemically a water-containing lead - iron - arsenite with additional chlorine ions .
Nealite is transparent and develops tabular to prismatic crystals of yellow to orange color, which are often arranged in radial or sheaf-shaped mineral aggregates . Nealit leaves a pale orange line on the whiteboard .
Etymology and history
Nealite was first discovered in the slag fields around the municipality of Lavrio in the Greek region of Attica and described in 1980 by Pete J. Dunn and Roland C. Rouse , who named the mineral after its discoverer Leo Neal Yedlin (1908-1997), a micromount mineral collector New Haven (Connecticut) , USA. Dunn and Rouse wanted to honor his selfless and extensive contributions to mineral samples with the naming. Leo Neal Yedlin liked to sacrifice some or all of the specimens he had collected when it was necessary for scientific studies.
The mineral's type material is held at the Smithsonian Institution in Washington, DC (Catalog No. # 137115).
classification
In the outdated but still partially in use 8th edition of the mineral classification by Strunz of Nealit belonged to the mineral class of "oxides and hydroxides" and then to the Department of "Arsenites (with As 3+ )" where he collaborated with Finnemanit , Freedit , Georgiadesit , Rouseit and Trigonit formed the unnamed group IV / J.03 .
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 Nealite to the class of "oxides and hydroxides" and there to the category of "arsenites, antimonites, bismuthites, sulfites , Selenite, tellurite; Iodate ”. However, this is further subdivided according to the possible presence of additional anions and water of crystallization (H 2 O), so that the mineral is classified according to its composition in the sub-section “Arsenite, Antimonite, Bismutite; with additional anions, with H 2 O ”, where it is the only member of the unnamed group 4.JD.05 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Nealit to the class of "phosphates, arsenates and vanadates" and there to the category of "anhydrous phosphates, etc., with hydroxyl or halogen". Here he is the only member of the unnamed group 04/04/06 within the sub-section “Anhydrous phosphates etc., with hydroxyl or halogen with (AB) 5 (XO 4 ) 2 Z q ”.
Crystal structure
Nealite crystallizes triclinically in the space group P 1 (space group no. 2) with the lattice parameters a = 6.55 Å ; b = 10.24 Å; c = 5.59 Å; α = 96.2 °; β = 89.6 ° and γ = 97.7 ° and one formula unit per unit cell .
Education and Locations
Nealite formed secondarily from ancient huts - cinders that interacted with seawater. As accompanying minerals may include Annabergit , aragonite , goethite , Georgiadesit and various Bleioxychloride occur.
As a rare mineral formation, Nealite could only be detected at a few sites, with around 20 sites known to date (as of 2015).
At its type locality , the slag discovery sites in the vicinity of the municipality of Lavrio , the mineral could be discovered at the following sites: Agios Nikolaos (St. Nicholas), Lavrio port, Oxygon, Panormos, Passa Limani, Posidonia, Sounion, Thorikos and Vrissaki.
In Germany, Nealit is known so far only from the Herzog Juliushütte near Astfeld in the Goslar district and from the slag heaps along the Silberbach near Oberschulenberg in Lower Saxony.
Other previously known sites are Menez-Plom (Carnoët) in the French department of Côtes-d'Armor , Carpenara in the Val Varenna in the metropolitan city of Genoa (Liguria) and the Gulf of Baratti near Populonia in the province of Livorno in Italy and the Haltcliff slag dump near Caldbeck Fells in the English county of Cumbria in the United Kingdom.
See also
literature
- Pete J. Dunn, Roland C. Rouse: Nealite a new mineral from Laurion, Greece. In: The Mineralogical Record. Volume 11 (1980), pp. 299–301 ( PDF 2.25 MB )
- G. Giuseppetti, F. Mazzi, C. Tadini: The crystal structure of nealite: Pb 4 Fe (AsO 3 ) 2 Cl 4 · 2H 2 O. In: Neues Jahrbuch für Mineralogie Monatshefte, 1993, pp. 278-288
- F. Pertlik, G. Schnorrer: A re-appraisal of the chemical formula of nealite, Pb 4 Fe (AsO 3 ) 2 Cl 4 · 2H 2 O on the basis of a crystal structure determination. In: Mineralogy and Petrology. 48: 193-200 (1993)
Web links
- Mineral Atlas: Nealit (Wiki)
- Webmineral - Nealite
- Database-of-Raman-spectroscopy - Nealite
- American-Mineralogist-Crystal-Structure-Database - Nealite
Individual evidence
- ↑ a b c d 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. 270 .
- ^ A b Pete J. Dunn, Roland C. Rouse: Nealite a new mineral from Laurion, Greece. In: The Mineralogical Record. Volume 11 (1980), pp. 299–301 ( PDF 2.25 MB )
- ↑ Mindat - Nealite
- ↑ Mineral Atlas: Nealit
- ↑ Find location list for Nealit in the Mineralienatlas and in Mindat