Mottramit
| Mottramit | |
|---|---|
 (size: 13.5 × 9.5 × 6.0 cm) |
|
| General and classification | |
| other names |
Vesbin |
| chemical formula |
|
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.BH.40 ( 8th edition : VII / B.27) 05.41.02.02 |
| Similar minerals | Descloizit , turanite |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | orthorhombic-dipyramidal; 2 / m 2 / m 2 / m |
| Room group (no.) | Pnam (No. 62) |
| Lattice parameters | a = 7.68 Å ; b = 9.32 Å; c = 6.05 Å |
| Formula units | Z = 4 |
| Frequent crystal faces | {111}, {101}, {201} |
| Physical Properties | |
| Mohs hardness | 3 to 3.5 |
| Density (g / cm 3 ) | measured: ≈ 5.9; calculated: 6.187 |
| Cleavage | no |
| Break ; Tenacity | small mussels to uneven; brittle |
| colour | grass green, olive green, yellowish green, siskin green, brownish red to brownish black to almost black |
| Line color | light yellow to yellowish green |
| transparency | transparent to almost opaque |
| shine | Glass gloss, matt |
| Crystal optics | |
| Refractive indices |
n α = 2.170 (2) n β = 2.260 (2) n γ = 2.320 (2) |
| Birefringence | δ = 0.150 |
| Optical character | biaxial negative |
| Axis angle | 2V = 73 ° (measured); 46 ° (calculated) |
| Pleochroism | weak to strong: X = Y = canary yellow to greenish yellow Z = brownish yellow |
Mottramit is a rather seldom occurring mineral from the mineral class of anhydrous phosphates with foreign anions. It crystallizes in the orthorhombic crystal system with the idealized composition PbCu [OH | VO 4 ].
Mottramit is the copper analogue of Descloizit (PbZn [OH | VO 4 ]) and forms a complete mixed series with it . In natural mottramite, a small amount of copper is therefore usually replaced ( substituted ) by zinc , which is expressed in the formula with element symbols in round brackets: Pb (Cu, Zn) [OH | VO 4 ]. In any mixing ratio, orthorhombic crystals with similar crystallographic and physical properties are formed. However, the color changes more and more into a brownish, almost black red, the higher the zinc content becomes. In the copper-rich Mottramit, on the other hand, the color is green to black-green.
The mineral usually develops crystals of different shapes, but also occurs in the form of grape, dendritic or massive aggregates as well as coasts and coatings. Often there are also various pseudomorphoses from mottramite to calcite or copper.
Etymology and history
Mottramit was first discovered near Alderley Edge and Mottram in the English county of Cheshire and at other localities. The mineral was described in 1876 by Henry Enfield Roscoe , who named it after the type locality Mottram.
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the mottramite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "anhydrous phosphates with foreign anions ", where it together with Arsendescloizit , Čechit , Descloizit and pyrobelonite the "Descloizitgruppe" with the system no. VII / B.27 .
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 Mottramite to the class of “phosphates, arsenates and vanadates” and there to the department of “phosphates etc. with additional anions ; without H 2 O “. However, this section is further subdivided according to the size of the cations involved and the molar ratio of the additional anions (OH, etc.) to the phosphate, arsenate or vanadate complex (RO 4 ), so that the mineral is classified in the sub-section “With medium-sized and mostly large cations; (OH etc.): RO 4 = 1: 1 ”can be found, where the“ descloicit group ”with the system no. 8.BH.40 and the other members Čechit, Descloizit and Pyrobelonit.
The systematics of minerals according to Dana also assigns the Mottramit to the class of "phosphates, arsenates and vanadates" and there to the category of "anhydrous phosphates etc., with hydroxyl or halogen". Here it is also part of the "descloicit group" with the system no. 41.05.02 and the other members Descloizit, Pyrobelonit, Čechit and Duftit-Alpha can be found in the subsection “ Anhydrous phosphates etc., with hydroxyl or halogen with (AB) 2 (XO4) Zq ”.
Education and Locations
Mottramit, like Descloizit, is a typical secondary mineral that is mainly formed by oxidation in lead-zinc-copper ore deposits . In addition to Descloizit, accompanying minerals include azurite , calcite , cerussite , dioptase , fragranceite , mimetite , vanadinite and wulfenite .
As a rather rare mineral formation, mottramite can sometimes be abundant at various sites, but overall it is not very common. Around 300 sites are known to date. In addition to its Mottram type locality, the mineral occurred in the United Kingdom in several locations in the counties of Cornwall , Cumbria and Leicestershire as well as in the "Pim Hill Mine" near Shrewsbury and in the "Judkins" quarry near Nuneaton in England. In Scotland Mottramit could be found in the area of Wanlockhead (Dumfries and Galloway) and Leadhills (Strathclyde).
Abundant mottramite finds are mainly known from the “ Tsumeb Mine” in Namibia, where, in addition to various parageneses , pseudomorphoses of calcite and copper also came to light.
In Germany, the mineral has so far mainly occurred in the Black Forest (e.g. Clara mine ) in Baden-Württemberg, in the Lautertal community in the Hessian Odenwald , near Bad Lauterberg and Sankt Andreasberg in Lower Saxony, in the "Ferdinande" mine near Heiligenhaus in the district Mettmann in North Rhine-Westphalia, in several places in the Eifel (Andernach, Ettringer Bellerberg), from North Rhine-Westphalia to Rhineland-Palatinate, near Krettnich / Wadern in Saarland, near Sayda and Schneeberg in the Saxon Ore Mountains and on the north coast of Helgoland in Schleswig -Holstein up.
In Austria, Mottramit has been found in the Kleinelendtal in the Ankogel group and in the Plachgraben in the Koralpe in Carinthia, at the Nasenkopf in the Habach Valley and in the “Stüblbau” pit in the Salzburg region of Lungau ( Tamsweg district ), in the basalt quarry in the Styrian municipality of Klöch and in the “Fuchsloch” pit in the Tyrolean part of the Inn Valley .
In Switzerland, Mottramit is so far only known from the Albigna glacier in the canton of Graubünden and from Saint-Luc VS in the canton of Valais.
Other locations include Argentina, Australia, Bolivia, Brazil, Chile, France, Gabon, Canada, Kyrgyzstan, the Democratic Republic of the Congo (Zaire), Italy, Japan, Madagascar, Morocco, Mexico, Namibia, Poland, Russia, Zambia, Sweden, Spain, South Africa, the Czech Republic and several states in the USA.
Calcite and Mottramite from the " Tsumeb Mine", Namibia
(size: 8.8 × 7.3 × 4.3 cm)
Mottramite pseudomorphism after calcite ... (size: 3.0 × 3.0 × 1.3 cm)
... and after copper from the same site (size: 3.1 × 1.2 × 0.2 cm)
Mottramite (greenish yellow) and chrysocolla (bluish) from the Long Chance & Vanelmart Mine, Mono County , California, USA ( overall size : 8.0 × 3.0 × 3.4 cm)
Crystal structure
Mottramite crystallizes orthorhombically in the space group Pnam (space group no. 62) with the lattice parameters a = 7.68 Å ; b = 9.32 Å and c = 6.05 Å and 4 formula units per unit cell .
use
Except as a mineral sample, mottramite has no particular economic significance.
See also
literature
- HE Roscoe: On two new vanadium minerals , In: Proceedings of the Royal Society of London , Volume 25 (1876), pp. 109–112 ( PDF 272 kB )
- MA Cooper, FC Hawthorne: The crystal structure of mottramite, and the nature of Cu ‹—› Zn solid solution in the mottramite-descloizite series , In: The Canadian Mineralogist , Volume 33 (1995), pp. 1119–1124 ( PDF 540 , 7 kB )
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 167 .
Web links
Individual evidence
- ↑ Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 .
- ↑ Mindat - Vesbin
- ↑ a b c IMA / CNMNC List of Mineral Names - Mottramite (PDF 1.3 MB; February 2013)
- ↑ 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. 459 .
- ↑ Webmineral - Mottramite
- ↑ Mottramite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ([PDF kB])
- ↑ a b c d e Mindat - Mottramite
- ↑ J. Ladurner, F. Purtscheller: The great mineral book . 2nd Edition. Pinguin Verlag, Innsbruck / Tirol, 1970, p. 108
- ^ HE Roscoe: On two new vanadium minerals , In: Proceedings of the Royal Society of London , Volume 25 (1876), pp. 109–112 ( PDF 272 kB )
- ↑ Find location list for Mottramit in the Mineralienatlas and in Mindat