Jalpait

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Jalpait
Jalpaite-rom38c.jpg
Jalpait crystal from the type locality Jalpa, Zacatecas, Mexico (size: 3.6 cm × 3.5 cm × 3.2 cm)
General and classification
chemical formula
  • CuAg 3 S 2
  • Oxide formula: Cu 2 S.3Ag 2 S
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.BA.25c ( 8th edition : II / B.05)
04/02/04/01
Crystallographic Data
Crystal system tetragonal
Crystal class ; symbol ditetragonal-dipyramidal
Room group (no.) I 4 1 / amd (No. 141)
Lattice parameters a  = 8.69  Å ; c  = 11.76 Å
Formula units Z  = 8
Physical Properties
Mohs hardness 2 to 2.5 (VHN 100 = 22.8 to 29.7)
Density (g / cm 3 ) measured: 6.82 to 6.85; calculated: 6.827
Cleavage well after the prism
Break ; Tenacity slightly mussel-like to hooked; Can be cut with a knife, cold deformable
colour light to dark gray, occasionally iridescent like chalcopyrite
Line color black
transparency opaque (opaque)
shine Metal gloss, matt

Jalpait is a rarely occurring mineral from the mineral class of "sulfides and sulfosalts". It crystallizes in the tetragonal crystal system with the chemical composition CuAg 3 S 2 and is thus chemically seen a copper - silver - sulfide .

Jalpait rarely develops prismatic, pseudocubic crystals . Mostly it occurs in coarse, irregular or leafy masses or in the form of grains and veins in other sulfides. The mineral is opaque in every form. Fresh samples are light to dark gray in color and have a metallic sheen on the surface . After a while, however, these usually turn black and become matt, but occasionally also have a colorful iridescence like chalcopyrite . On the other hand, Jalpait always leaves a black line on the whiteboard .

With a Mohs hardness of 2 to 2.5, jalpait is one of the soft minerals that, like the reference mineral gypsum (2), can just be scratched with a fingernail. Its fracture behavior is similar to that of metals, the fracture surfaces are therefore usually elongated with hooks and the mineral can be cold-formed due to its toughness .


Etymology and history

Jalpait was first discovered in the "Mina la Leonora" near the city of Jalpa in the Mexican state of Zacatecas and described in 1858 by August Breithaupt , who named the mineral after its type of locality . The chemical analysis was carried out by Robert Richter (1823–1869), in which he determined a silver content of 71.51, a copper content of 13.12, a sulfur content of 14.36 and small amounts of iron of about 0.79% by weight which after calculating the iron corresponds almost exactly to the current composition.

Type material of the mineral is kept in the Mineralogical Collection of the TU Bergakademie Freiberg (Register No. 4705 / E 3.1) and at the Mines ParisTech (English National School of Mines ) in Paris.

classification

Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the jalpait belonged to the mineral class of "sulfides and sulfosalts" and there to the division of "sulfides, selenides and tellurides with a ratio of metal: S, Se, Te> 1: 1 ", where together with Brodtkorbit , Eukairit , Henryit , Imiterit , Mckinstryit , Selenojalpait and Stromeyerit the" Stromeyerit-Eukairit-Gruppe "with the system no. II / B.06 .

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 Jalpait to the category of "Metal sulfides, M: S> 1: 1 (mainly 2: 1)". However, 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 copper (Cu), silver (Ag), gold (Au)", where it can only be found together with Selenojalpait forms the unnamed group 2.BA.25c .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Jalpait to the class of "sulfides and sulfosalts" and there in the department of "sulfide minerals". Here it can also be found together with Selenojalpait in the unnamed group 02.04.04 within the subsection “Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 2: 1” .

Education and Locations

Jalpait crystal with small nests of green, unknown crystals (weathering product) from the type locality Jalpa, Zacatecas, Mexico (size: 3.6 cm × 3.5 cm × 3.2 cm)

Jalpaite formed hydrothermally in ore - transitions at low temperatures (below 117 ° C). As accompanying minerals may include Akanthit , chalcopyrite , galena , Mckinstryit , Pearceit , Polybasit , pyrite , quartz , sterling silver , sphalerite , Stromeyerite , tetrahedrite and Tennantit occur.

As a rare mineral formation, Jalpait could only be detected at a few sites, with around 100 sites being known to date (as of 2014). In addition to its type locality, the "Mina la Leonora" near the city of Jalpa in Zacatecas, the mineral occurred in Mexico at La Mesa in Chihuahua , in the " Tayoltita Mine" in Durango , the "Cata Mine" (De Cata Mine) near Guanajuato in the state of the same name, the "Mololoa Mine" at Hostotipaquillo in Jalisco and at Tepic in Nayarit.

In Germany, Jalpait has so far only been found in the Clara mine near Oberwolfach in Baden-Württemberg, in the quarries on Glasberg and Emmertsberg in the municipality of Mühltal in Hesse and in the Mansfeld Basin in Saxony-Anhalt.

In Greenland, the mineral was found grown in galena in the cryolite deposit near Ivittuut .

Other locations are in Australia, Bolivia, Bulgaria, Chile, China, El Salvador, France, Indonesia, Ireland, Italy, Japan, Canada, Kazakhstan, Malaysia, New Caledonia, Norway, Peru, Poland, Russia, Slovakia, the Czech Republic, Hungary and the United States of America (USA).

The "Caribou Mine" near Caribou in the US state of Colorado , where crystals with a diameter of up to three centimeters emerged, is known for its extraordinary Jalpait finds .

Crystal structure

Jalpait crystallizes tetragonally in the space group I 4 1 / amd (space group no. 141) with the lattice parameters a  = 8.69  Å and c  = 11.76 Å as well as 8 formula units per unit cell .

See also

literature

Web links

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

Individual evidence

  1. ↑ a b c d e 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.  65 .
  2. ↑ a b Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p.  302 .
  3. ↑ a b c Jalpaite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF kB )
  4. ↑ August Breithaupt : Jalpait. In: Berg- und Hüttenmännische Zeitung. Volume 17 (1858), pp. 85-86 ( available online in the Google book search)
  5. ↑ Webmineral - Jalpaite
  6. ↑ Type mineral catalog of the University of Hamburg - Jalpait
  7. ↑ Mindat - Number of localities for Jalpait
  8. ↑ Find location list for Jalpait at the Mineralienatlas and at Mindat
  9. ↑ Petr Korbel, Milan Novák: Mineral Encyclopedia . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 25 ( Dörfler Natur ).