Aguilarite

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Aguilarite
Aguilarite - San Carlos Mine, La Luz, Guanajuato, Mexico.jpg
Aguilarite from the San Carlos Pit, La Luz, Guanajuato, Mexico - Size: 3.9 cm
General and classification
chemical formula Ag 4 SeS
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.BA.30b ( 8th edition : II / B.05)
04/02/01/03
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-disphenoidal; 222
Space group P 2 1 2 1 2 1
Lattice parameters a  = 4.33  Å ; b  = 7.09 Å; c  = 7.76 Å
Formula units Z  = 2
Physical Properties
Mohs hardness 2.5
Density (g / cm 3 ) measured: 7.40 to 7.53; calculated: 7.65
Cleavage no
Break ; Tenacity hooked
colour lead gray
Line color grey black
transparency opaque
shine Metallic luster

Aguilarite is a very rarely occurring mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the orthorhombic crystal system with the chemical composition Ag 4 SeS and forms skeletal, pseudododecahedral, pseudocubic or pseudo-octahedral crystals , but also massive mineral aggregates and adhesions with acanthite or naumannite .

Fresh crystal surfaces shine in a light, metallic lead gray. However, exposed to the ambient air, they turn black after a while.

Etymology and history

Was first discovered Aguilarit in the "pit San Carlos" in La Luz in the Mexican state of Guanajuato and described in 1891 by Friedrich August Genth , who named the minerals by Ponciano Aguilar (1853-1935), the administrator of the type locality "pit San Carlos".

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the aguilarite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfides with a molar ratio of metal: sulfur, selenium, tellurium> 1: 1", where together with acanthite, argentite , benleonardite , cervelleite , empressite , hessite , chenguodaite ( IMA2004-042a ), naumannite, tsnigriite and supportite, the unnamed group II / B.05 formed.

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 aguilarite to the class of "sulfides and sulfosalts" and there in the department of "metal sulfides, M: S> 1: 1 (mainly 2: 1) ”. However, this section is further subdivided according to the type of cations involved , so that the mineral can be found in accordance with its composition in the subdivision "with copper (Cu), silver (Ag), gold (Au)", where it can only be found together with Naumannit forms the unnamed group 2.BA.30b .

The systematics of minerals according to Dana also assigns the aguilarite to the class of "sulfides and sulfosalts" and there in the department of "sulfide minerals". Here it is together with acanthite and naumannite in the "acanthite group" with system no. 04/02/01 within the subdivision “ 04/02 Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 2: 1 ”.

Education and Locations

Aguilarit formed at relatively low temperatures in hydrothermal , silver - and selenium-rich but low-sulfur deposits . Accompanying minerals include acanthite, calcite , naumannite, prostite , pearceite , quartz , silver and stephanite .

So far (as of 2011), Aguilarite has been found at around 60 sites worldwide. The best developed and with up to 3 cm length also the largest crystal finds were made in his type locality "Grube San Carlos" (La Luz) and in Chontalpan (Guerrero), but also in the mine Peñafiel near Guanajuato , which is also near La Luz located "Pit Santa Rita", the "Pit Nino Perdido" near Nayal and the "Pit Flores de María" near Rayas (all in the state of Guanajuato) were found aguilarite.

Other sites are Jagué ( La Rioja in Argentina); Hubei , Inner Mongolia Autonomous Region and Sichuan Autonomous Region in China; Bohemia and Moravia in the Czech Republic; the Indonesian islands of Java and Sumatra ; the Japanese islands of Hokkaidō , Honshū and Kyūshū ; the North Island of New Zealand; the Far Eastern Federal District in Russia, the desert Kyzyl Kum in Uzbekistan as well as the US states Colorado , Idaho , Nevada , Utah and Washington .

Crystal structure

Aguilarite crystallizes orthorhombically in the space group P 2 1 2 1 2 1 with the lattice parameters a  = 4.33  Å ; b  = 7.09 Å and c  = 7.76 Å and 2 formula units per unit cell .

See also

Individual evidence

  1. ↑ a b c Webmineral - Aguilarite (English)
  2. ^ Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 66 .
  3. ^ Friedrich August Genth: Contributions to mineralogy - 1. Aguilarite, a new species. In: American Journal of Science. 1891, pp. 402-402 ( full text ).
  4. ↑ Mindat - Aguilarite (English)
  5. ^ Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 66 .

literature

Web links

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