Pyrolusite
| Pyrolusite | |
|---|---|
 |
|
| General and classification | |
| other names |
Soft manganese ore |
| chemical formula | β-MnO 2 |
|
Mineral class (and possibly department) |
Oxides and hydroxides |
|
System no. to Strunz and to Dana |
4.DB.05 ( 8th edition : VIII / C.02) 04.04.01.04 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | 4 / mmm |
| Space group | P 4 2 / mnm (No. 136) |
| Lattice parameters | a = 4.40 Å ; c = 2.88 Å |
| Formula units | Z = 2 |
| Twinning | rarely along {031}, {032} |
| Physical Properties | |
| Mohs hardness | 6 to 6.5 (2 if solid) |
| Density (g / cm 3 ) | 4.7 to 5.1 |
| Cleavage | perfectly |
| Break ; Tenacity | shell-like |
| colour | dark gray, steel gray, black |
| Line color | black |
| transparency | opaque |
| shine | Metallic luster |
| Other properties | |
| Chemical behavior | soluble in HCl with evolution of chlorine |
Pyrolusite , also known as soft manganese ore or chemically as manganese (IV) oxide , is a frequently occurring mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the tetragonal crystal system with the chemical composition MnO 2 and mostly forms dendritic , stalactitic, grape-like, granular or powdery masses of dark gray to black color. If the formation conditions are favorable, prismatic, needle-like, striped crystals that are up to eight centimeters in size can also arise.
Etymology and history
The name of the pyrolusite was chosen after the Greek words πυρος pyros for fire and λούω lou washing, as it was used to remove colors from glass.
Oxidic manganese ores have been known for a long time. In 1822 August Breithaupt divided these into three minerals, soft manganese ore (later pyrolusite), glossy manganese ore (later manganite ) and light gray manganese ore . After further investigations he called the latter polianite . Wilhelm Ritter von Haidinger found out, however, that this is only a variety of pyrolusite.
classification
In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the pyrolusite belonged to the department of "Oxides with the molar ratio of metal: oxygen = 1: 2 (MO 2 and related compounds)", where together with argutite , cassiterite , Paratellurite , plattnerite , rutile and tripuhyite the "rutile group" with the system no. IV / D.02 formed.
The 9th edition of Strunz's mineral systematics , which has been in force since 2001 and is used by the International Mineralogical Association (IMA), also classifies pyrolusite in the category of "Oxides with a metal: oxygen ratio = 1: 2 and comparable". However, this is further subdivided according to the relative size of the cations involved and the crystal structure, so that the mineral can be classified according to its composition in the sub-section “With medium-sized cations; Chains of edge-linked octahedra "can be found where, together with argutite, cassiterite, plattnerite, rutile, tripuhyite, tugarinovite and varlamoffite, the" rutile group "with the system no. 4.DB.05 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns pyrolusite to the class of "oxides and hydroxides" and there in the "oxides" category. Here it is together with argutite, ilmenorutil, cassiterite, plattnerite, rutile, squawcreekite , stishovite and struverite in the "rutile group (tetragonal: P 4 / mnm )" with the system no. 04.04.01 to be found in the subsection of " Simple oxides with a cation charge of 4+ (AO 2 ) ".
Crystal structure
Pyrolusite crystallizes in the tetragonal crystal system in the space group P 4 2 / mnm (space group no. 136) with the lattice parameters a = 4.40 Å and c = 2.88 Å, as well as two formula units per unit cell .
properties
Pyrolusite is infusible in front of the soldering tube, but gives off oxygen . If a borax bead is used, it turns blue. Pyrolusite is soluble in hydrochloric acid, with the development of chlorine . In contrast to the very similar manganite, pyrolusite leaves a black line on the marking board .
Modifications and varieties
The compound MnO 2 is trimorphic , that is, it crystallizes apart from in tetragonal symmetry as pyrolusite also in hexagonal symmetry as Akhtenskite and in orthorhombic symmetry as Ramsdellite .
There are two known varieties of Pyrolusites. These are the morphological polianite variety , which is a pseudomorphism from pyrolusite to manganite, and an unnamed silver-bearing variety.
Wad , on the other hand, is a mixture of minerals made up of various soft manganese oxides , but mostly pyrolusite.
Education and Locations
Pyrolysite is formed in manganese ores under strongly oxidizing, hydrothermal conditions. The mineral can also form in swamps and shallow lakes and as a weathering product of manganite. It is associated with manganite, hollandite , hausmannite , braunite , chalcophanite , goethite and hematite .
Pyrolysite is a common manganese ore and many sites are known. The better known include Elgersburg , Friedrichroda and Oehrenstock in Thuringia , Eibenstock in Saxony , Gießen in Hesse , Oberroßbach and Bad Marienberg in Rhineland-Palatinate , Horní Blatná in the Czech Republic , Markhemville and Hillsborough in Canada , Ironwood , Leadville , Lake Valley and the Artillery Mountains in the United States . Manganese nodules consist to a large extent of pyrolusite.
use
Pyrolusite is an important manganese ore for the extraction of the metal. It is also used as a black pigment for ceramics and glass .
See also
literature
- Pyrolusites . 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; 70 kB ; accessed on October 30, 2019]).
- Entry to pyrolusite. In: Römpp Online . Georg Thieme Verlag, accessed on January 2, 2015.
Web links
- Mineral Atlas: Pyrolusite
- Pyrolusites. In: mindat.org. Hudson Institute of Mineralogy, accessed October 30, 2019 .
Individual evidence
- ↑ a b c d 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. 207 (English).
- ↑ a b c Pyrolusite . 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; 70 kB ; accessed on October 30, 2019]).
- ↑ A. Breithaupt: XV. Concerning the manganese ores, the crystallization of which belongs to the holohedral division of the rhombic crystallization system . In: Annals of Physics and Chemistry . tape 61 , 1844, pp. 187–200 ( gallica.bnf.fr [accessed October 30, 2019]).
- ↑ R. Köchlin: Investigations on Manganite, Polianite and Pyrolusite . In: Journal of Crystallography, Mineralogy and Petrography . tape 9 , no. 1 , 1888, p. 22–46 , doi : 10.1007 / BF02994477 ( link.springer.com [accessed October 30, 2019]).
- ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 534-536 (first edition: 1891).
- ^ Polianite. In: mindat.org. Hudson Institute of Mineralogy, accessed October 30, 2019 .
- ↑ Argentiferous Pyrolusite. In: mindat.org. Hudson Institute of Mineralogy, accessed October 30, 2019 .
- ↑ 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 .
- ↑ a b Pyrolusite . In: Römpp Chemie Lexikon , Thieme-Verlag, as of March 2002.