Crookesit
| Crookesit | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Cu 7 TlSe 4 |
|
Mineral class (and possibly department) |
Sulfides and sulfosalts |
|
System no. to Strunz and to Dana |
2.BD.50 ( 8th edition : II / B.03) 04/02/12/01 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | tetragonal-disphenoidic; 4th |
| Space group | I 4 (No. 82) |
| Lattice parameters | a = 10.45 Å ; c = 3.93 Å |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 2.5 to 3.0 |
| Density (g / cm 3 ) | measured: 6.90; calculated: 7.443 |
| Cleavage | Well |
| Break ; Tenacity | not defined |
| colour | lead gray to bluish gray |
| Line color | not defined |
| transparency | opaque |
| shine | Metallic luster |
Crookesite is a rarely occurring mineral from the mineral class of "sulfides and sulfosalts" (including selenides, tellurides, arsenides, antimonides, bismuthides, sulfarsenites, sulfantimonites, sulfbismuthites) with the chemical composition Cu 7 TlSe 4 and is therefore a copper - thallium - selenide which is structurally related to the sulphide minerals.
Crookesite crystallizes in the tetragonal crystal system , but has so far only been found in the form of finely divided inclusions , granular aggregates or small veins of lead-gray to bluish-gray color. He is in every form opaque ( opaque ) and has a metallic luster on.
Etymology and history
The mineral was first discovered in the ore deposit of the "Skrikerum" mine near Valdemarsvik in the Swedish province of Östergötland County and described in 1867 by Adolf Erik Nordenskiöld . It is named after the discoverer of the chemical element thallium, Sir William Crookes .
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the crookesite belonged to the division of "sulfides, selenides and tellurides with the molar ratio of metal : sulfur , selenium , tellurium > 1: 1", where it together with athabascaite , bellidoite , Berzelianite , sabatierite and umangite formed the unnamed group II / B.03 .
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 classifies crookesite in the category of "Metal sulfides, M: S> 1: 1 (mainly 2: 1)". This is, however, 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 mercury (Hg), thallium (Tl)", where it is the only member of the unnamed group 2.BD .50 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the crookesite to the class of "sulfides and sulfosalts" and there in the department of "sulfide minerals". Here it can be found together with sabatierite in the unnamed group 02.04.12 within the subsection "Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 2: 1".
Crystal structure
Crookesite crystallizes tetragonally in space group I 4 (space group no. 82) with the lattice parameters a = 10.45 Å and c = 3.93 Å as well as two formula units per unit cell .
Education and Locations
Crookesite formed under hydrothermal conditions and usually occurs with other selenides as Umangite , Berzelianit , Eukairit , Klockmannit , Clausthalit and Sabatierit , but also with selenhaltigem linneite , calcite and quartz associated to.
As a rare mineral formation, crookesite could only be detected at a few sites, whereby so far (as of 2013) around 10 sites are known. Its type locality "Skrikerum" near Valdemarsvik is the only known site in Sweden so far .
In Germany , crookesite has so far only been found in the “Brummerjan” pits near Zorge and “Weintraube” near Lerbach in Lower Saxony .
In Switzerland , the mineral could in rock samples at one of the Nagra carried out bore near Kaisten and at a test well in a "Redbed" -Lagerstätte (by finely divided hematite intense red colored sand or clay rock) Weier field near Rheinfelden in the canton of Aargau be detected .
Other previously known sites are the “Tumiñico Mine” in the Sierra de Cacho in the Argentine province of La Rioja , the “Chibukla” deposit in Armenia , and the “Sanpu” ore field in the Suixi district (Huaibei) in the Chinese province of Anhui and Nové Město na Moravě -Petrovice and Rožná in the Czech Kraj Vysočina .
See also
literature
- AE Nordenskiöld: Sur les minéraux sélénifères et thallifères de Skrikerum . In: Bulletin Mensuel de la Société Chimique de Paris . tape 7 , 1867, p. 409–414 ( rruff.info [PDF; 389 kB ; accessed on March 19, 2018]).
- JW Early: Description and synthesis of the selenide minerals . In: American Mineralogist . tape 35 , 1950, pp. 337–364 ( rruff.info [PDF; 1.9 MB ; accessed on March 19, 2018]).
Web links
- Mineral Atlas: Crookesite (Wiki)
- Mindat - Crookesite
- Database-of-Raman-spectroscopy - Crookesite
- American-Mineralogist-Crystal-Structure-Database - Crookesite
Individual evidence
- ↑ 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. 73 .
- ↑ Webmineral - Crookesite
- ↑ Crookesite . 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; 61 kB ; accessed on March 19, 2018]).
- ↑ Förteckning öfver AE Nordenskiöld skrifter . Utarbetad af JM Hulth ( Memento from September 29, 2015 in the Internet Archive ) (PDF 246.7 kB; translation: list of AE Nordenskiöld's writings . Prepared by JM Hulth; full name "Nils Adolf Erik Nordenskiöld", p. 2; first description " Crookesit "1867, p. 5)
- ↑ Mindat - Number of localities for Crookesite
- ↑ Find location list for Crookesite at the Mineralienatlas and at Mindat