Carminite
| Carminite | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | PbFe 3+ 2 [OH | AsO 4 ] 2 |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.BH.30 ( 8th edition : VII / B.28) 10.41.06.01 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | orthorhombic-dipyramidal; 2 / m 2 / m 2 / m |
| Space group | Cccm (No. 66) |
| Lattice parameters | a = 16.60 Å ; b = 7.59 Å; c = 12.27 Å |
| Formula units | Z = 8 |
| Frequent crystal faces | {010}, {110}, {011} |
| Physical Properties | |
| Mohs hardness | 3.5 |
| Density (g / cm 3 ) | measured: 5.03 to 5.18 (average 5.22); calculated: 5.405 |
| Cleavage | clearly after {110} |
| Break ; Tenacity | shell-like to uneven; brittle |
| colour | carmine red (name!), brick red, reddish brown |
| Line color | reddish yellow |
| transparency | translucent |
| shine | Glass luster, pearlescent luster on cleavage surfaces |
| Crystal optics | |
| Refractive indices |
n α = 2.050 to 2.070 n β = 2.050 to 2.070 n γ = 2.060 to 2.080 |
| Birefringence | δ = 0.010 |
| Optical character | biaxial positive |
| Pleochroism | visible: X = light yellowish red Y = dark carmine red Z = dark carmine red |
Carminite is a relatively rare mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the orthorhombic crystal system with the chemical composition PbFe 3+ 2 [OH | AsO 4 ] 2 , so from a chemical point of view it is a lead - iron arsenate with additional hydroxide ions .
Carminite is translucent and usually develops needle-like to tabular crystals with a characteristic carmine-red or brick-red to reddish-brown color with reddish-yellow streak color . The single crystals are predominantly arranged in spherical or tufted aggregates . In addition, carminite also occurs in the form of fibrous to massive aggregates. Unharmed crystal surfaces have a glass-like sheen , whereas cleavage surfaces have a more mother-of-pearl shimmer.
With a Mohs hardness of 3.5, carminite is one of the medium-hard minerals that, like the reference mineral fluorite (4), can be easily scratched with a pocket knife .
Etymology and history
The mineral was first discovered in the iron ore mine Grube Louise near Niedersteinebach in Rhineland-Palatinate and described in 1850 by Fridolin Sandberger , who originally called it carmine spath because of its characteristic color . In the German-language specialist literature, however, the term carminite, which is closer to the Arabic-Persian word origin kermes for pokeweed ( scarlet berry ), prevailed, while in the English-language carminite .
classification
In the meantime outdated, but still in use 8th edition of the mineral classification by Strunz of Karminit to the department belonged "water clear phosphates, with foreign anions F, Cl, O, OH," where he along with Attakolith , Bertossait , Leningradit , Namibit , Paganoit , Palermoit and Sewardit formed the unnamed group VII / B.28 .
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 carminite to the category of “phosphates etc. with additional anions; without 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 (OH etc.) to the phosphate, arsenate or vanadate complex (RO 4 ), so that the mineral can be classified in the sub-section “With medium-sized and mostly large cations; (OH etc.): RO 4 = 1: 1 "can be found, where only together with Sewardit the" carminite group "named after him with the system no. 8.BH.30 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns carminite to the class of "phosphates, arsenates and vanadates" and there to the category of "anhydrous phosphates etc. with hydroxyl or halogen". Here he is together with Sewardit in the " carminite group " with the system no. 41.10.06 within the subsection "Anhydrous phosphates etc., with hydroxyl or halogen with (A 2+ B 2+ ) 3 (XO 4 ) 2 Z q ".
Crystal structure
Carminite crystallizes isotypically with palermoite in the orthorhombic crystal system in the space group Cccm (space group no. 66) with the lattice parameters a = 16.60 Å ; b = 7.59 Å and c = 12.27 Å and 8 formula units per unit cell .
properties
In front of the soldering tube on carbon, carminite can be melted very easily into steel-gray slag with strong development of arsenic vapors . With soda you get grains of lead and the borax pearl shows strong coloring from iron. When heated in a flask over a spirit flame, however, the mineral does not change.
Carminite is easily soluble in concentrated, heated hydrochloric acid and nitric acid and forms a golden yellow liquid. A caustic potash solution can remove arsenic acid from the mineral.
Modifications and varieties
The connection PbFe 3+ 2 [OH | AsO 4 ] 2 is dimorphic and still occurs in nature in addition to the orthorhombic crystallized modification Karminit as monoclinic crystallizing Mawbyit ago.
Education and Locations
(field of view: 5 × 5 mm)
Carminite is secondary to the weathering of arsenopyrite in some oxidized lead-containing mineral deposits . As accompanying minerals may include Anglesite , Arseniosiderit , Bayldonit , Beudantit , Cerussite , Dussertit , Mimetite , plumbojarosite , Skorodit and Wulfenit occur.
As a rather rare mineral formation, carminite can sometimes be abundant at different sites, but overall it is not very common. So far (as of 2013) around 170 sites are known. In addition to its type locality Grube Louise near Niedersteinebach , the mineral appeared in Rhineland-Palatinate in the mines “Clemenslust” near Kasbach (Kasbach-Ohlenberg) , “Schöne Aussicht” near Dernbach (Neuwied district) and “Friedrichssegen” near Frücht . It was also found in several places in the Black Forest ( Clara mine, Silberbrünnle mine, Geigeshalde) in Baden-Württemberg, near Hagendorf (municipality of Waidhaus ) in Bavaria, on Katzenstein and Hohenstein in the Hessian Lautertal (Odenwald) , near Sankt Andreasberg in Lower Saxony , in the Wilder Mann mine near Müsen in North Rhine-Westphalia and in several places in the Saxon Ore Mountains (Altväter mines including Eschig, Sauberg).
In Austria Karminit could previously only on Strassegg -Pass near gases and the Prince Kogel in the community affairs Kaltenegg be found in Styria.
The only known site in Switzerland so far is the Hochmättli on Mürtschenalp in the canton of Glarus .
Other sites are found in Algeria, Australia, Belgium, China, France, Greece, Italy, Japan, Kazakhstan, Mexico, Mongolia, Namibia, Poland, Portugal, Spain, South Africa, the United Kingdom (England), the Czech Republic, Hungary and the United States of America (Alabama, Alaska, Arizona, Colorado, California, Maine, Montana, Nevada, New Mexico, Utah).
See also
literature
- F. Sandberger : Carminspath, a new mineral from the order of the arseniates , In: Annalen der Physik und Chemie , Volume 80 (1850), pp. 391–392 ( PDF 103.1 kB )
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Dörfler Verlag GmbH, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 168 .
Web links
- Mineral Atlas: Carminite (Wiki)
- Database-of-Raman-spectroscopy - Carminite
- American-Mineralogist-Crystal-Structure-Database - Carminite
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 , p. 643 .
- ↑ 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. 457 .
- ↑ Webmineral - Carminite
- ↑ Carminite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 66.4 kB )
- ↑ a b c Mindat - Carminite
- ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 633 (first edition: 1891).
- ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
- ↑ a b F. Sandberger : Carminspath, a new mineral from the order of the arseniates , In: Annalen der Physik und Chemie , Volume 80 (1850), pp. 391–392 ( PDF 103.1 kB )
- ↑ Mindat - Number of localities for Carminite
- ↑ Find location list for carminite ( Carminite ) at the Mineralienatlas and at Mindat