Lammerite
| Lammerite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1980-016 |
| chemical formula |
|
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.AB.30 ( 8th edition : VII / A.09) 03/38/09/01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Room group (no.) | P 2 1 / a (No. 14) |
| Lattice parameters |
a = 5.08 Å ; b = 11.61 Å; c = 5.39 Å β = 111.7 ° |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 3.5 to 4 |
| Density (g / cm 3 ) | measured: 4.9 to 5.18; calculated: 5.263 |
| Cleavage | completely after {010}; imperfect after {001}; good after {100} |
| Break ; Tenacity | not defined |
| colour | dark green |
| Line color | light green |
| transparency | transparent |
| shine | Diamond luster, glass luster on cleavage surfaces |
| Crystal optics | |
| Refractive indices |
n α = 1.89 n β = 1.90 to 2.06 n γ = 1.95 to 2.14 |
| Birefringence | δ = 0.06 |
| Optical character | biaxial positive |
| Axis angle | 2V = measured: 54 (5) °; calculated: 50 ° |
| Pleochroism | strong: X = light blue; Y = sky blue; Z = light bluish green |
Lammerite is a very rarely occurring mineral from the mineral class of "phosphates, arsenates and vanadates". It crystallizes in the monoclinic crystal system with the chemical composition Cu 3 (AsO 4 ) 2 and is therefore, chemically speaking, copper (II) arsenate .
Lammerite is transparent and develops only small, tabular to prismatic crystals up to about two millimeters in size, dark green in color with light green streak color . It is mostly found in the form of radial or spherulitic mineral aggregates . Unharmed crystal surfaces show a diamond-like sheen . This is a little less on cleavage surfaces and is more similar to that of glass.
With a Mohs hardness of 3.5 to 4, it roughly corresponds to the reference mineral fluorite and is therefore just as easy to scratch with a pocket knife .
Etymology and history
Lammerite was first discovered in the Laurani copper mine in the Bolivian department of La Paz and described in 1981 by Paul Keller , Werner H. Paar and Pete J. Dunn , who named the mineral after the Austrian mineral collector Franz Lammer.
Type material of the mineral is in the Institute for Mineralogy and Crystal Chemistry of the University of Stuttgart in Germany, in the Natural History Museum in London (Catalog No. 1980,357), at Harvard University in Cambridge, Massachusetts (Catalog No. 117006) and at National Museum of Natural History in Washington, DC (Catalog No. 146966, 148264).
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the lammerite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the division of "anhydrous phosphates [PO 4 ] 3− , without foreign anions", where together with Stranskiit and Xanthiosit the unnamed group VII / A.09 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 lammerite 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 sub-section “With medium-sized cations”, where it is the only member of the unnamed group 8.AB.30 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns lammerite to the class of "phosphates, arsenates and vanadates" and there in the department of "anhydrous phosphates, etc.". Here he is to be found as the only member / together with in the unnamed group 38.03.09 within the sub-section "Anhydrous phosphates etc., (A + B 2+ ) 3 (XO 4 ) 2 ".
Education and Locations
Lammerite usually forms in the oxidation zone of hydrothermal , polymetallic deposits , but can also arise as a sublimation product from volcanic gases . Depending on the locality can be used as accompanying minerals among others Alarsit , Anglesite , anhydrite , Atlasovit , Chalkanthit , Chalkocyanit , Dolerophanit , Euchlorin , Fedotovit , hematite , Klyuchevskit , langbeinite , Leightonit , Leningradit , Melanothallit , Nabokoit , Olivenit , Tolbachit and Tenorite occur.
So far (as of 2014) only about 10 sites are known where lammerite samples were found. In Bolivia, for example, apart from its type locality , the Laurani copper mine in the La Paz department, it has only been found in the Pulacayo mine in the canton of Huanchaca (Potosí).
The only place of discovery in Germany so far is the zinc hut Münsterbusch near Stolberg in the Aachen Revier (North Rhine-Westphalia) and the only place of discovery in Austria so far is the Abraham tunnel on Silberberg near Rattenberg in Tyrol.
Other well-known lammerite mines are the Abundancia and El Guanaco mines near Santa Catalina in the Antofagasta region and the Veta Negra mine in the Pampa Larga (Tierra Amarilla) in the Atacama region in Chile, the well-known Tsumeb mine and the nearby slag heaps in the Oshikoto region of Namibia and the Yadovitaya- fumarole on the second cinder cones in the so-called "big fissure eruption" ( Great Fissure ) of the volcano Tolbachik on the Kamchatka peninsula in Russia.
Crystal structure
Lammerite crystallizes monoclinically in the space group P 2 1 / a (space group no. 14) with the lattice parameters a = 5.08 Å ; b = 11.61 Å; c = 5.39 Å and β = 111.7 ° and two formula units per unit cell .
See also
literature
- P. Keller, WH Paar, PJ Dunn: Lammerite, Cu 3 [AsO 4 ] 2 , a new mineral from Laurani, Bolivia. In: Tschermaks Mineralogische und Petrographische Mitteilungen. Volume 28 (1981), pp. 157-164
- Michael Fleischer , Roger G. Burns, Louis J. Cabri, Carl A. Francis, Adolf Pabst : New mineral names. In: American Mineralogist. Volume 67 (1982), pp. 413-418 ( PDF 550.1 kB ; p. 3)
Web links
- Mineral Atlas: Lammerite (Wiki)
- Mindat - Lammerite
- Web mineral - Lammerite
- Database-of-Raman-spectroscopy - Lammerite
- American-Mineralogist-Crystal-Structure-Database - Lammerite
Individual evidence
- ↑ a b IMA / CNMNC List of Mineral Names; March 2014 (PDF 1.5 MB)
- ↑ 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. 428 .
- ↑ a b c d e f Lammerite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 65.2 kB )
- ↑ List of localities for lammerite in the Mineralienatlas and Mindat