Eskimoit
| Eskimoit | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1976-005 |
| chemical formula | Ag 7 Pb 10 Bi 15 S 36 |
|
Mineral class (and possibly department) |
Sulfides and sulfosalts |
|
System no. to Strunz and to Dana |
2.JB.40b ( 8th edition : II / E.31) 06/03/02/01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m or monoclinic; m |
| Space group | C 2 / m (No. 12) or Cm (No. 8) |
| Lattice parameters |
a = 13.46 Å ; b = 4.10 Å; c = 30.19 Å β = 93.4 ° |
| Formula units | Z = 1 |
| Twinning | lamellar twins according to [001] |
| Physical Properties | |
| Mohs hardness | 3 to 3.5; (VHN 50 = 162 to 223) |
| Density (g / cm 3 ) | calculated: 7.12 |
| Cleavage | not defined |
| Break ; Tenacity | not defined |
| colour | Gray; in polished sections under incident light "galena white" |
| Line color | not defined |
| transparency | opaque |
| shine | Metallic luster |
Eskimoite is a rarely occurring mineral from the mineral class of "sulfides and sulfosalts". It crystallizes in the monoclinic crystal system with the chemical composition Ag 7 Pb 10 Bi 15 S 36 , so it is a compound of silver , lead , bismuth and sulfur , which structurally belongs to the sulfosalts .
Eskimoite is opaque in every form and has so far only been found in the form of lamellar grains and mineral aggregates of gray, metallic shimmering color. In polished sections, however , the mineral appears “ galena white ” under the incident light microscope .
Etymology and history
Was first discovered in the Eskimoit cryolite - deposit of Ivittuut in the southwest of Greenland and 1977. Makovicky by E. and S. Karup-Møller, the mineral according to the ethnic group of Eskimos who colonized designated as the first Greenland.
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the Eskimoite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfosalts (S: As, Sb, Bi = x)", where it belongs together with Bursait (discredited 2006), Gustavit , Lillianit , Ourayit , Schirmerit (discredited 2008), Treasurit , Vikingit and Xiligolith the "Lillianit series" with the system no. II / E.31 .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), classifies the Eskimoit in the department of “sulfosalts with PbS as a model”. This is further divided by the crystal structure, so that the mineral according to its composition in the subsection "galena derivatives with lead (Pb)" to find where it together with Aschamalmit and Heyrovskýit the unnamed group 2.JB.40b forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Eskimoite to the class of "sulfides" and there to the department of "sulfosalts". Here he is the only member of the unnamed group 06/03/02 within the subdivision “ Sulphonic salts with the ratio 2.0 <z / y <2.49 and the composition (A + ) i (A 2+ ) j [B y C z ], A = metals, B = semimetals, C = non-metals ”.
Crystal structure
Eskimoite crystallizes monoclinically in the space group C 2 / m (space group no. 12) or Cm (no. 8) with the lattice parameters a = 13.46 Å ; b = 4.10 Å; c = 30.19 Å and β = 93.4 ° and one formula unit per unit cell .
Education and Locations
Eskimoite forms berryite in cryolite deposits, but can also generally arise in gold, silver and lead ore deposits. Aikinite , enargite , galena and pyrite appear as accompanying minerals .
As a rare mineral formation, Eskimoite could only be detected at a few localities, although slightly more than 10 localities are known so far (as of 2014). Its type locality Ivittuut is the only known site in Greenland to date.
In Germany, Eskimoit has so far only been found in the “Friedrich-Christian” mine near Bad Rippoldsau-Schapbach in Baden-Württemberg and in the “Buchberg” quarry near Naundorf in the Central Saxony district .
In Austria, the mineral was found in the ancient “Milleiten” silver mine near Zirknitz in the Goldberg group in Carinthia as well as in the Erzwies mine in the Gastein Valley and on the Rauriser Goldberg near Kolm-Saigurn in the Hüttwinkltal ( Rauris Valley ) in Salzburg.
Eskimoit is also known from the La Mothe quarry near La Roche-Balue in the Loire-Atlantique department in France, from the Ikuno mine near Asago on the Japanese island of Honshū, in the “Văratec” deposit near Băiuț in Romania, in the Au- Ag-Te deposit Kochbulak near Angren in Uzbekistan as well as some locations in various states of the USA.
See also
literature
- E. Makovicky, S. Karup-Moller: Chemistry and crystallography of the lillianite homologous series. II. Definition of new minerals eskimoite, vikingite, ourayite and treasurite. Redefinition of schirmerite and new data on the lillianite-gustavite solid-solution series . In: New Yearbook for Mineralogy. Treatises . tape 131 , 1977, pp. 56-82 (English).
Web links
- Mineral Atlas: Eskimoite (Wiki)
- Eskimoite. In: mindat.org. Hudson Institute of Mineralogy, accessed December 21, 2018 .
- David Barthelmy: Eskimoite Mineral Data. In: webmineral.com. Retrieved December 21, 2018 .
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. 143 .
- ↑ a b c d Eskimoite . 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; 63 kB ; accessed on December 21, 2018]).
- ↑ 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 .
- ↑ Mindat - Number of localities for Eskimoit
- ↑ Find location list for Eskimoite at the Mineralienatlas and at Mindat