Coronadite

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Coronadite
Pyromorphite-Coronadite-146089.jpg
Pyromorphite and Coronadite found at Broken Hill , New South Wales , Australia
General and classification
chemical formula Pb (Mn 4+ 6 , Mn 3+ 2 ) O 16
Mineral class
(and possibly department) 		Oxides and hydroxides
System no. to Strunz
and to Dana 		4.DK.05a ( 8th edition : IV / D.08)
09/07/04/01
Similar minerals Hollandit , crypto melan
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group I 2 / m (No. 12, position 3)Template: room group / 12.3
Lattice parameters a  = 9.938  Å ; b  = 2.8678 Å; c  = 9.834 Å
β  = 90.39 °
Formula units Z  = 1
Physical Properties
Mohs hardness 4.5 to 5
Density (g / cm 3 ) measured: 5.41-5.51; calculated: 5.431
Cleavage Please complete!
colour Black-metallic, white with reflected light
Line color Brownish black
transparency opaque
shine Metallic gloss, also matt
Crystal optics
Optical character strongly anisotropic
Pleochroism very pronounced, dark brown to gray
Other properties
Chemical behavior soluble in acids

Coronadite is a common mineral from the mineral class of oxides and hydroxides . It crystallizes in the monoclinic crystal system with the chemical composition Pb (Mn 4+ 6 , Mn 3+ 2 ) O 16 . It therefore consists of lead (28%), manganese (49%) and oxygen (23%). The mineral forms fibrous, grape-shaped aggregates .

Etymology and history

The mineral was discovered in 1904 by W. Lindgren and WF Hillebrand in the Coronado Mine in Arizona , USA . In 1923, the independence of the mineral was questioned by Ernst Emerson Fairbanks , according to whose theory coronadite was a mixture of hollandite and an unknown mineral. However, this could not be confirmed, so that the mineral today counts and is recognized as independent.

The mine in which the coronadite was found is named after the Spanish conquistador Francisco Vasquez de Coronado (1500–1554) who discovered and explored the south-west of America . It is therefore not clear whether the mineral is named after that discoverer or after the type locality (location of the first description), the Coronado mine.

The mineral was discovered prior to the formation of the CNMNC and is therefore grandfathered .

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the coronadite belonged to the mineral class of "oxides and hydroxides" and there to the department of "oxides with metal to oxygen in a ratio of 1 to 2", where it was included in the cryptomelane - Group with the system no. IV / D.08 and the other members Manjiroit , Kryptomelan, Strontiomelan , Priderit , Henrymeyerit , Mannardit , Redledgeit , Hollandit and Cesàrolith .

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 coronadite to the class of "oxides and hydroxides" and there into the department of "metal oxides with the molar ratio M: O ≤ 1: 2 “. This is, however, further subdivided according to the metal ions that dominate the compound, so that the mineral can be found according to its composition in the sub-section "with large (and medium-sized) cations ", where the "Coronadite group" that has now been created is named after the system -No. 4.DK.05a and its other members are Ferrihollandit , Hollandit, Kryptomelan, Manjiroit and Strontiomelan.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the coronadite to the class of "oxides and hydroxides" and there in the department of "multiple oxides". There he forms the "cryptomelan group" with Hollandit, Kryptomelan, Manjiroit, Strontiomelan and Henrymeyerit.

Crystal structure

Coronadite crystallizes monoclinically in the space group I 2 / m (space group no. 12, position 3) with the lattice parameters a  = 9.938  Å , b  = 2.8678 Å and c  = 9.834 Å as well as one formula unit per unit cell . The crystal structure of Coronadit is comparable to that of Hollandit. Template: room group / 12.3

properties

Chemical properties

Coronadite readily soluble in acids . The mineral can also contain traces of aluminum oxide , silicon dioxide , iron (III) oxide and copper (II) oxide . Depending on the location, the admixtures are more or less pronounced.

Physical Properties

Coronadit has a pronounced pleochroism . It appears dark brown to gray.

Education and Locations

Coronadite, along with smithsonite , found at Broken Hill , New South Wales , Australia

Coronadite often occurs together with hollandite, pyrolusite and other manganese minerals.

Coronadite can be found in around 200 locations.

The type locality is the Coronado Mine in Arizona, USA.

In Germany this occurs in some federal states. In Baden-Württemberg there are three sites in the Black Forest ( Gengenbach , Titisee-Neustadt and Wolfach ), as well as in the Kaiserstuhl mountains in Bötzingen and in Kraichgau in Bruchsal . In Bavaria there is a place of discovery in the Upper Palatinate in Freihung . In Lower Saxony there is a site in Clausthal-Zellerfeld in the Harz Mountains . In North Rhine-Westphalia there is a site in Engelskirchen in the Bergisches Land and in Eiserfeld and Neunkirchen in Siegerland . In Rhineland-Palatinate there is one site in the Hunsrück , one in the Lahn valley and one in the Westerwald . In Saxony there is a site in Callenberg .

There is a place of discovery in Austria . This is in East Tyrol in the Kalsertal .

In Switzerland there is a site in the canton of Valais in Fäld .

Otherwise Coronadit can be used in Australia , Bolivia , Brazil , Bulgaria , Chile , China , France , Greece , Hungary , India , Indonesia , Iran , Ireland , Italy , Japan , Jordan , Kazakhstan , Kosovo , Mexico , Mongolia , Morocco , Namibia , Norway , Portugal , Romania , Russia , Zambia , Slovakia , South Africa , Spain , Togo , the Czech Republic , Ukraine , the United Kingdom , the United States of America, and Uzbekistan can be found.

See also

literature

  • Clifford Frondel , EWM Heinrich: New data on hetaerolite, hydrohetaerolite, coronadite, and hollandite . In: American mineralogist . Vol. 27, 1942, pp. 42-56 ( PDF ).
  • John W. Gruner: The chemical relationship of cryptomelan (psilomelan), hollandite, and coronadite . In: American mineralogist . Vol. 28, 1943, pp. 497-506 ( PDF ).
  • Jeffery E. Post, David L. Bisch: Rietveld refinement of the coronadite structure . In: American Mineralogist . Vol. 72, 1989, pp. 913-917 ( PDF ).
  • DF Hawett: Coronadite; modes of occurrence and origin . In: Economic Geology . Vol. 66, 1971, pp. 164-177 , doi : 10.2113 / gsecongeo.66.1.164 .

Web links

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

Individual evidence

  1. ^ A b Jeffery E. Post, David L. Bisch: Rietveld refinement of the coronadite structure. In: American Mineralogist. , Vol. 72, 1989, pp. 913–917 ( PDF , English)
  2. ↑ a b Cliffort Frondel, EWM Heinrich: New data on hetaerolite, hydrohetaerolite, coronadite, and hollandite. In: American mineralogist. , Vol. 27, 1942, pp. 42–56 ( PDF )
  3. ↑ a b c d e f g h i Coronadite. In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy , Mineralogical Society of America. 2001 ( PDF 66.9 kB ).
  4. ↑ a b c d e f g h Mindat - Coronadite (English)
  5. ↑ Webmineral - Coronadite
  6. ↑ a b c Mineral Atlas: Coronadite