Christite

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Christite
Christite.jpg
Christite (dark red) in a matrix of light red realgar and yellow aura pigment from Shimen , Hunan Province, China
General and classification
other names

IMA 1976-015

chemical formula TlHg [AsS 3 ]
Mineral class
(and possibly department)
Sulfides and sulfosalts
System no. to Strunz
and to Dana
2nd HDD.15 ( 8th edition : II / E.12)
04/03/10/01
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group P 2 1 / n (No. 14, position 2)Template: room group / 14.2
Lattice parameters a  = 6.11  Å ; b  = 16.19 Å; c  = 16.19 Å
β  = 96.7 °
Formula units Z  = 4
Physical Properties
Mohs hardness 1 to 2
Density (g / cm 3 ) measured: 6.15; calculated: 6.37
Cleavage perfect after {010}, very good after {110} and {001}, good after { 1 01}
colour light orange to dark carmine red
Line color light orange to yellow
transparency translucent to opaque
shine Diamond luster

Christite is a very seldom occurring thallium - mercury - mineral with the chemical composition TlHg [AsS 3 ] and is therefore chemically a thallium-mercury arsenide . Due to the chemical relationship between arsenides and sulphides , Christite belongs to the mineral class of "sulphides and sulphosalts ".

Christite crystallizes in the monoclinic crystal system , but has so far only been found in the form of small, poorly developed crystal grains up to about one millimeter in size. The mineral is translucent to opaque and has a light orange to dark crimson color. It's similar to Realgar's , but darker. Christit leaves a light orange to yellow line on the marking board .

Etymology and history

Christite was first discovered in the "Carlin Gold Mine" near Elko in the Lynn District, Eureka County in the US state of Nevada. The mineral was described in 1977 by Arthur S. Radtke, Frank W. Dickson, John F. Slack and Kevin L. Brown, who named the mineral after Charles Louis Christ (1916–1980) in recognition of his outstanding contributions in the areas of crystallography, Appreciate mineralogy and geochemistry.

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , Christite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfosalts", where together with Ellisit , Erniggliit , Hatchit , Laffittit , Routhierit , Sicherheitsit , Stalderite and Wallisite formed the unnamed group II / E.12 .

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 Christite to the class of "sulfides and sulfosalts", but in the newly defined department of "sulfosalts with SnS as a model " a. This is further subdivided according to the predominant metals in the compound, so that the mineral can be found according to its composition in the sub-section "With Thallium (Tl)", where it is the only member of the unnamed group 2.HD.15 .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Christite to the class of "sulfides and sulfosalts" and there in the department of "sulfosalts". Here it is together with laffittite and daliranite in the unnamed group 04/03/10 within the subsection “Sulphosalts with the ratio 3> z / y and the composition (A +) i (A2 +) j [ByCz], A = metals, B = semi-metals , C = non-metals ”.

Crystal structure

Christite crystallizes monoclinically in the space group P 2 1 / n (space group no. 14, position 2) with the lattice parameters a  = 6.11  Å ; b  = 16.19 Å; c  = 16.19 Å and β = 96.7 ° and 4 formula units per unit cell . Template: room group / 14.2

The structure consists of AsS 3 pyramids, which are connected by HgS 4 tetrahedra to form a two-dimensional layer parallel {010}. The thallium atoms lie between the layers and hold them together through weak bonds, which also explains the complete cleavage observed according to {010}.

Education and Locations

Christit normally develops with realgar , orpiment and Lorandite socialized in hydrothermal barite - veins and mineralized carbonaceous silty dolomite rocks and thallium-rich Erzlinsen in stratabound mercury deposits. Other accompanying minerals include getchellite , marcasite and pyrite .

Since Christite is one of the very rare mineral formations, it has so far (as of 2018) only been documented in a few samples from less than 10 sites. In addition to its “Carlin Gold Mine” type locality near Elko, the mineral was also found in the US in the “Getchell Mine” near Adam Peak in Humboldt County (Nevada) , in the Lanmuchang Tl (Hg) deposit in the Xingren district in the Chinese province Guizhou, in the “Zareh Shuran Mine” near Takab in the Iranian province of West Azerbaijan and near Allchar (Alsar) in the Macedonian district of Roszdan .

See also

literature

  • Arthur S. Radtke, Frank W. Dickson, John F. Slack, Kevin L. Brown: Christite, a new thallium mineral from the Carlin gold deposit, Nevada . In: American Mineralogist . tape 62 , 1977, pp. 421-425 ( minsocam.org [PDF; 479 kB ; accessed on June 4, 2018]).
  • Kevin L. Brown, Frank W. Dickson: The crystal structure of synthetic christite, HgTlAsS 3 . In: Journal of Crystallography . tape 144 , 1976, pp. 367–376 ( arizona.edu [PDF; 434 kB ; accessed on June 4, 2018]).

Web links

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

Individual evidence

  1. 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.  121 .
  2. Webmineral - Christite (English)
  3. a b Christite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 64  kB ; accessed on June 4, 2018]).
  4. Kevin L. Brown, Frank W. Dickson: The crystal structure of synthetic christite, HgTlAsS 3 . In: Journal of Crystallography . tape 144 , 1976, pp. 367–376 ( arizona.edu [PDF; 434 kB ; accessed on June 4, 2018]).
  5. Find location list for Christite in the Mineralienatlas and Mindat