Scorodite
| Scorodite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Fe 3+ [AsO 4 ] • 2H 2 O |
|
Mineral class (and possibly department) |
Phosphates, arsenates, vanadates |
|
System no. to Strunz and to Dana |
8th CD.10 ( 8th edition : VII / C.05b) 04/40/01/03 |
| 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 = 8.94 Å ; b = 10.28 Å; c = 10.00 Å |
| Formula units | Z = 8 |
| Frequent crystal faces | (111), (100), (201), 101, (001) |
| Physical Properties | |
| Mohs hardness | 3.5 to 4 |
| Density (g / cm 3 ) | measured: 3.27; calculated: 3.276 |
| Cleavage | imperfect after {201}; indistinct after {001} and {100} |
| Break ; Tenacity | slightly mussel-like |
| colour | colorless, gray, greenish, light blue, violet, red, yellow-brown |
| Line color | light green |
| transparency | transparent translucent |
| shine | Glass gloss to weak diamond gloss, resin gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.741 to 1.784 n β = 1.744 to 1.805 n γ = 1.768 to 1.820 |
| Birefringence | δ = 0.027 to 0.036 |
| Optical character | biaxial positive |
| Axis angle | 2V = 40 ° to 75 ° (measured), 46 ° to 80 ° (calculated) |
Scorodite is a frequently occurring mineral from the mineral class of "phosphates, arsenates and vanadates" with the chemical composition Fe 3+ [AsO 4 ] · 2H 2 O and is therefore chemically a water-containing iron - arsenate , more precisely iron (III) arsenate .
Scorodite crystallizes in the orthorhombic crystal system and develops only small, prismatic or dipyramidal crystals , but also grape-like, granular to massive aggregates or crusty coatings. Pseudo-hexagonal shapes due to twinning are also known.
His glass-resin to shiny crystals are either colorless or foreign admixtures colored gray, greenish in various degrees of saturation, bluish, reddish or yellowish brown. Scorodites with the so-called alexandrite effect , a color change from blue in daylight to purple or yellow-green in artificial light, are also rarely found.
Scorodite is dimorphic with parascorodite and forms a complete mixed series with mansfieldite .
Etymology and history
Skorodit was due to the after garlic smelling arsenic fumes when crushed or heating after the Greek word σκορόδιου ( Scorodion named) "garlic".
Skorodit was first found and described by August Breithaupt in 1818 in the Stamm Asser mine ( am Graul ) near Langenberg , Erzgebirgskreis , in Saxony.
classification
Already in the outdated 8th edition of the mineral classification according to Strunz , the scorodite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates without foreign anions ", where together with mansfieldite , strictite and variscite it belonged to the "variscite- Row "with the system no. VII / C.05b within the "Klinovariscit-Variscit-Gruppe" (VII / C.05).
In the Lapis mineral directory according to Stefan Weiß, which, out of consideration for private collectors and institutional collections, is still based on this form of Karl Hugo Strunz's system , the mineral received the system and mineral number. VII / C.09-80 . In the “Lapis system” this also corresponds to the section “Phosphates containing water, without foreign anions”, where scorodite together with Kolbeckite , Koninckite , Malhmoodite (formerly Mahlmoodite ), Mansfieldite, Metavariscite , Parascorodite , Phosphosiderite , Strengite, Variscite, Yanomamite and Zigrasite forms the "Variscit Group" (as of 2018).
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and was updated by the International Mineralogical Association (IMA) until 2009, also classifies the scorodite under the category of “phosphates etc.” without 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 anion complex (RO 4 ) to the water of crystallization , so that the mineral is classified according to its composition in the subsection “With only medium-sized cations; RO 4 : H 2 O = 1: 2 ”is to be found where, together with Mansfieldite, Redondite, Strengit, Variscite and Yanomamit, the“ Variscite group ”with the system no. 8.CD.10 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking area , also assigns the scorodite to the class of "phosphates, arsenates and vanadates" and there in the department of "water-containing phosphates etc.". Here he is the only member / together with in the " Variscit group " with the system no. 40.04.01 to be found in the sub-section "Water-containing phosphates etc., with A 3+ XO 4 × x (H 2 O)".
Crystal structure
Scorodite is isotypic with strictite , that is, both crystallize in the orthorhombic crystal system in the space group Pcab (space group no. 61, position 2) . The lattice parameters differ, however, and for scorodite are a = 8.94 Å , b = 10.28 Å and c = 10.00 Å with eight formula units per unit cell .
Education and Locations
Scorodite is a typical secondary mineral that forms in the oxidation zone of iron - and arsenic - containing ore deposits . Accompanying minerals include adamin , arseniosiderite , arsenopyrite , austinite , beudantite , dussertite , goethite , carminite , lollingite , pharmacosiderite , pyrite and vivianite .
In Germany, in addition to its type locality Langenberg (Saxony), the mineral was also found in Baden-Württemberg (Black Forest, Odenwald), Bavaria (Fichtelgebirge, Upper Palatinate Forest), Hesse (Odenwald), Lower Saxony (Harz), North Rhine-Westphalia (Sauerland, Siegerland), Rhineland-Palatinate (Lahntal, Siegerland, Westerwald), Saxony-Anhalt (Harz) and Thuringia (Bad Lobenstein, Saalfeld).
Scorodite was found to be a frequent mineral formation in many places, with around 1200 sites being documented so far (as of 2019).
So far, scorodite has been found in the following places worldwide: Constantine (Djebel Debar) in Algeria; La Rioja and San Juan in Argentina; several regions in Australia ; Luxembourg Province in Belgium; Departamento Cochabamba , Departamento La Paz , Departamento Oruro and Departamento Potosí in Bolivia; Goiás and Minas Gerais in Brazil; Haskovo Oblast in Bulgaria; Antofagasta , Atacama and Coquimbo in Chile; several provinces in the People's Republic of China ; in western Finland ; in many regions of France ; Attica in Greece; England and Wales in Great Britain ; Azerbaijan in Iran; Cork and Galway in Ireland; several regions in Italy ; Honshū , Kyūshū, and the Nansei Islands in Japan; New Brunswick , Ontario and Yukon in Canada; at Balqash in Kazakhstan; Niari in the Republic of the Congo; Toliara in Madagascar; Souss-Massa-Draâ in Morocco; among others in Durango in Mexico; Damaraland , Erongo and Tsumeb in Namibia; Akershus and Nordland in Norway; Ancash and Huánuco in Peru; Silesia in Poland; some regions in Portugal ; some provinces in Hungary ; the provinces of Tashkent and Fargʻona in Uzbekistan; Carinthia , Salzburg , Styria and Upper Austria ; Chukotka in Russia ; Lapland and Södermanland in Sweden; Canton of Valais in Switzerland; some regions in Slovakia ; Trojane in Slovenia; including Andalusia and Catalonia in Spain; several provinces in South Africa ; Taiwan ; Turkey ; Bohemia and Moravia in the Czech Republic; as well as many regions in the US .
use
Skorodite used to be used together with arsenopyrite as a raw material for the production of rat poison and insecticides containing arsenic .
See also
literature
- Paul Ramdohr , Hugo Strunz : Klockmann's textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, 1978, ISBN 3-432-82986-8 , pp. 641 .
Web links
- Mineral Atlas: Scorodite (Wiki)
- Scorodite search results. In: rruff.info. Database of Raman spectroscopy, X-ray diffraction and chemistry of minerals (RRUFF), accessed December 26, 2019 .
- American-Mineralogist-Crystal-Structure-Database - Scorodite. In: rruff.geo.arizona.edu. Retrieved December 26, 2019 .
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 , p. 478 (English).
- ↑ David Barthelmy: scorodite MineralData. In: webmineral.com. Retrieved December 26, 2019 .
- ↑ a b c d Scorodite . 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; 68 kB ; accessed on December 26, 2019]).
- ↑ a b c d e Scorodite. In: mindat.org. Hudson Institute of Mineralogy, accessed December 26, 2019 .
- ↑ Stefan Weiß: Blue Scorodite from Hemerdon: "Specimen Mining" in the south-west of England . In: Lapis mineral magazine . Volume 25, volume 10 . Weise, October 2000, ISSN 0176-1285 , p. 37 .
- ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
- ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1816 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed December 26, 2019 .
- ↑ Localities for scorodite. In: mindat.org. Hudson Institute of Mineralogy, accessed December 26, 2019 .
- ↑ Find location list for scorodite in the Mineralienatlas and Mindat , accessed on December 26, 2019.