Crypto melan

Crypto melan
	Cryptomelan from Morocco
General and classification
other names	Ebelmenit; Barium Potassium Psilomelan;
chemical formula	K (Mn 4+ 7 Mn 3+ ) O 16 ; KMn 8 O 16 ;
Mineral class; (and possibly department)	Oxides and hydroxides
System no. to Strunz ; and to Dana	4.DK.10 ( 8th edition : IV / D.08) ; 07.09.01.02
Crystallographic Data
Crystal system	monoclinic
Crystal class ; symbol	monoclinic prismatic; 2 / m
Space group	I 4 / m (No. 87)
Lattice parameters	a = 9.956 Å ; b = 2.8705 Å; c = 9.706 Å ; β = 90.95 °
Formula units	Z = 1
Twinning	an (010) or (10 1 ), forms pseudo-tetragonal units
Physical Properties
Mohs hardness	6 - 6.5
Density (g / cm 3 )	measured: 4.17-4.41; calculated: 4.44
Cleavage	Please complete
colour	Steel gray to bluish gray
Line color	brownish black
transparency	opaque
shine	metallic to matt
Crystal optics
Optical character	almost isotropic
Other properties
Chemical behavior	soluble in hydrochloric acid (HCl)

Kryptomelan (also ebelmenite ) is a relatively common mineral of the mineral class of oxides and hydroxides with the chemical composition K (Mn ⁴⁺₇ Mn ³⁺ ) O ₁₆ and thus, chemically speaking, a potassium - manganese oxide.

Kryptomelan crystallizes in the monoclinic crystal system and rarely develops subhedral crystals up to 2 mm in size, more often they are finely ground grains or grape-shaped to fibrous aggregates .

Etymology and history

The mineral was first known only as a component of psilomelan in 1942 . Only through detailed investigations could it be found out that psilomelan is not independent, but a mixture of different manganese oxides, including cryptomelan. The mineral name was coined by Wallace D. Richmond and Michael Fleischer , who first described the mineral. It is derived from the Greek words for "hidden" and "black".

classification

In the outdated but still in use 8th edition of the systematics of minerals according to Strunz , cryptomelan is classified in the mineral class of oxides and hydroxides. This is based on the ratio of metal to oxygen, so that the mineral is, according to its formula, in the group "Oxides with a ratio of metal : oxygen = 1: 2 (MO ₂ and related compounds)". The cryptomelan forms the "cryptomelan group" named after it, together with Cesàrolith , Coronadit , Henrymeyerit , Hollandit , Manjiroit , Mannardit , Priderit , Redledgeit and Strontiomelan . The mineral ankangite , which was formerly also part of this , has been a variety of mannardite since it was discredited in 2012 .

In the comprehensively revised 9th edition of the Systematics of Minerals according to Strunz , which is also used by the International Mineralogical Association (IMA), the mineral is also classified in the class of oxides and hydroxides. This is initially also subdivided according to the ratio of metal to oxygen. Cryptomelan is also in the group "Metal: Oxygen = 1: 2 and comparable". However, this is now further subdivided according to the size of the cations involved so that the mineral falls into the subgroup “With large (± medium-sized) cations; Tunnel structures "can be found. There he also forms the "cryptomelan group", but now Romanèchit , Strontiomelan and Todorokit belong to it.

In the systematics of minerals according to Dana , cryptomelan is classified in the group of "multiple oxides" (No. 07). There it is classified in the subgroup of system number 09 (which is also called "multiple oxides"). Within these, it also forms a "cryptomelane group" with Hollandite, Manjiroite, Coronadite, Strontiomelan and Henrymeyerite. It has the system number 07.09.01.02

Chemism

A chemical analysis of cryptomelan showed a proportion of water of crystallization of up to 3.5%. The Handbook of Mineralogy of the Mineralogical Society of America speaks of the empirical formula (K _0.94 Na _0.25 Sr _0.13 Ba _0.10 Mg _0.03 ) _{Σ = 1.45} (Mn ⁴⁺_6.33 Mn ³⁺_{1 , 20} Fe ³⁺_0.30 Al _0.15 ) _{Σ = 7.98} (O, OH) ₁₆ . The first description by Richmond and Fleischer comes to the same conclusion.

Crystal structure

Kryptomelan crystallizes monoclinically in the space group I 4 / m (space group no. 87) with the lattice parameters a = 9.916 Å , b = 2.864 Å and c = 2.864 Å as well as one formula unit per unit cell . Template: room group / 87

Education and Locations

There are 580 sources of crypto melan. The type locality of Kryptomelan located in Tombstone , Tombstone District, Arizona , USA .

There are also many sites in Germany . There are five sites in Baden-Württemberg in the Black Forest . There are several sites in Bavaria , both in Franconia and in the Upper Palatinate . There are several small sites in Hessen in the Odenwald , and another one in Hessen is in Wetzlar . There are also two sites in Lower Saxony in the Harz Mountains , in Clausthal-Zellerfeld and in Lautenthal . In North Rhine-Westphalia there is one site in the Sauerland and two more in the Siegerland . There are also two sites in Rhineland-Palatinate . There is also a site in Saarland , it is in Krettnich zu Wadern . There is also a site in Saxony-Anhalt , also in the Harz near Wernigerode . In Saxony in the Ore Mountains there are at least seven sites, in Upper Lusatia there are five more. In Thuringia , in localities also Thuringian Forest there are three.

There are also a number of sites in Austria . There is one site in Friesach in Carinthia, and there is also one site each in the Koralpe and Packalpe ranges . In the province of Salzburg one site and possibly another one. In Styria , there are three sites in East Tyrol ( Tyrol ) another.

In Switzerland there are two sites. One of them is in the canton of Graubünden in Oberhalbstein , the second in the canton of Valais in Saint-Luc zu Anniviers .

There are occurrences of cryptomelan on all continents. In addition to the sites already mentioned, there are occurrences in Egypt , Argentina , Australia , Belgium , Bolivia , Bosnia and Herzegovina , Brazil , Burkina Faso , Chile , China , Fiji , France , Gabon , Ghana , Greece , Greenland , India , Ireland , Israel , Italy , Japan , Jordan , Canada , Kazakhstan , Cuba , Madagascar , Mexico , Mongolia , Morocco , Mozambique , Namibia , New Caledonia , New Zealand , Niger , Norway , Poland , Portugal , Romania , Russia , Rwanda , Slovenia , South Africa , Spain , Togo , the Czech Republic , Turkey , Hungary , Ukraine , the United Kingdom and the United States of America .

use

Newer Dyson air purifiers use cryptomelane to neutralize formaldehyde , whereby the mineral does not have to be replaced.

literature

Wallace D. Richmond, Michael Fleischer : Cryptomelane, a new name for the commonest of the "psilomelane" minerals . In: American Mineralogist . tape 27 , 1942, pp. 607–610 (English, minsocam.org [PDF; 246 kB ; accessed on August 16, 2020]).
Lewis Steven Ramsdell: The unit cell of cryptomelane . In: American Mineralogist . tape 27 , 1942, pp. 611–613 (English, minsocam.org [PDF; 185 kB ; accessed on August 18, 2020]).
Lawrence T. Larson: Geology and mineralogy of certain manganese oxide deposits . In: Economic Geology . tape 59 , 1964, pp. 54-78 , doi : 10.2113 / gsecongeo.59.1.54 (English).

Web links

Commons : Cryptomelane - collection of images, videos and audio files

Crypto melan. In: Mineralienatlas Lexikon. Stefan Schorn u. a., accessed on August 18, 2020 .
American-Mineralogist-Crystal-Structure-Database - Cryptomelane. In: rruff.geo.arizona.edu. Accessed August 18, 2020 .

Individual evidence

↑ ^a ^b ^c ^d ^e ^f Cryptomelane. In: mindat.org. Hudson Institute of Mineralogy, accessed August 18, 2020 .
↑ ^a ^b Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: July 2020. (PDF; 2.44 MB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, July 2020, accessed August 16, 2020 .
^ 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. 227 (English).
↑ ^a ^b ^c ^d ^e ^f ^g Cryptomelane . 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; 74 kB ; accessed on August 18, 2020]).
↑ crypto-melan. In: Mineralienatlas Lexikon. Stefan Schorn u. a., accessed on August 18, 2020 .
^ ^A ^b Wallace D. Richmond, Michael Fleischer : Cryptomelane, a new name for the commonest of the "psilomelane" minerals . In: American Mineralogist . tape 27 , 1942, pp. 607–610 (English, minsocam.org [PDF; 246 kB ; accessed on August 16, 2020]).
↑ Dyson Pure Cool Cryptomic. In: testberichte.de. February 12, 2020, accessed August 18, 2020 .

[Mindat-1] ↑ ^a ^b ^c ^d ^e ^f Cryptomelane. In: mindat.org. Hudson Institute of Mineralogy, accessed August 18, 2020 .

[IMA-Liste-2020-07-2] Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: July 2020. (PDF; 2.44 MB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, July 2020, accessed August 16, 2020 .

[StrunzNickel-3] 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. 227 (English).

[Datenblatt-4] ↑ ^a ^b ^c ^d ^e ^f ^g Cryptomelane . 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; 74 kB ; accessed on August 18, 2020]).

[MA-5] crypto-melan. In: Mineralienatlas Lexikon. Stefan Schorn u. a., accessed on August 18, 2020 .

[RichmondFleischer-6] A ^b Wallace D. Richmond, Michael Fleischer : Cryptomelane, a new name for the commonest of the "psilomelane" minerals . In: American Mineralogist . tape 27 , 1942, pp. 607–610 (English, minsocam.org [PDF; 246 kB ; accessed on August 16, 2020]).

[testberichte.de-7] Dyson Pure Cool Cryptomic. In: testberichte.de. February 12, 2020, accessed August 18, 2020 .