Pyrargyrite

• Aerosit
• Antimony silver bezel
• Dark Rotgültig or Dark Rotgültigerz

Pyrargyrite, outdated also known as Dark Rotgültig ( ore ), antimony silver bezel or Aerosit, is a commonly occurring mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the trigonal crystal system with the chemical composition Ag3 [ SbS3 ] and belongs structurally to the sulfosalts of silver and antimony.

Pyrargyrite most developed prismatic or rhombohedral crystals, but is found also in granular form to massive aggregates of dark red to gray-black color. The mostly translucent or entirely opaque Pyrargyritkristalle point to the crystal faces adamantine. The cleavage is depending on the direction of cleavage clearly { 1011 } { 0112 according to very indistinct }.

Special Features

When exposed to light of the first red to dark red colored Pyrargyrite darkens with time until it appears almost black. However, the stroke color remains cherry and thus enables next to its low Mohs hardness of 2.5 and a density of 5.85 g / cm ³ identification of the mineral.

Pyrargyrite mainly contains silver ( 59.75 %), antimony ( 22.48 % ) and sulfur ( 17.76 %). Chance may also be contained arsenic.

Between Pyrargyrite and the related Proustite ( Ag3 [ ASS3 ] ) is up to a minimum temperature of 360 ° C a complete solid-solution series.

Etymology and history

The well-known since the 16th century, albeit in different forms of writing traditional designation Rotgültig or Rotgültigerz (also ertz red gold, rod gulden ertz, red Güldenes ore and similar ) initially consisted of two different, but similar looking minerals, namely the Pyrargyrite and the Proustite. Was named the ore due to its striking red color, its iris -like luster and its high silver content of nearly 60 %.

Since 1789, after Abraham Gottlob Werner between dark and sparse Rotgiltigerz distinction, however, was only 1804, the chemist Joseph Louis Proust by its chemical analyzes clarify that the Rotgültigerze of antimony ( Dark, Ag3SbS3 ) and arsenic (light, Ag3AsS3 ) are two distinct minerals.

The final name of Pyrargyrite for the Dark Rotgültigerz coined in 1831 Ernst Friedrich Glocker after the two ancient Greek words πῦρ [PUR ] for " fire" and ἄργυρος [ argyros ] for " silver " because of its ability to easily be melted a silver grain before the blowpipe.

The synonym Aerosit gave Selb in 1805 a "on the kolywänschen silver mine in Siberia occurring, dark Rotgültigerz ".

Classification

Already in the now outdated but still in use 8th edition of the mineral classification by Strunz was one of Pyrargyrite to the class' sulfides and sulfosalts "and then to the general department of " thio (S: As, Sb, Bi = x) ", where he together with Proustite, Pyrostilpnit, Quadratit, Samsonit and Xanthokon the unnamed group II/E.07 formed.

The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the Pyrargyrite also in the class of " sulfides and sulfosalts ," there, however, in the newly defined division of " Sulfoarsenide, Sulfoantimonide and Sulfobismuthide " a. This is also further divided according to the crystal structure, so that the mineral is found in accordance with its construction in the subdivision of " island ( Neso ) Sulfarsenide etc. without additional sulfur (S ) " where there is only together with Proustite the unnamed group 2.GA.05 forms.

The mainly common in English-speaking classification of minerals according to Dana assigns the Pyrargyrite in the class of " sulfides and sulfosalts " and then in the Department of " thio " one. Here he is with Proustite in the designated pursuant to this mineral " Proustitgruppe " with the System No. 03:04:01 within the sub-division of " sulfosalts with the ratio 3 > z / y and the composition (A ) i ( A2 ) j [ Bycz ], A ​​= metals, semimetals B =, C = to find non-metals ".

Education and Locations

Pyrargyrite often forms in hydrothermal veins. Magnificent crystals of Pyrargyrite are found in some deposits in Germany, especially in Sankt Andreas Berg and in Freiberg and other places in the Saxon Erzgebirge. Considerable evidence comes from Slovakia, Bohemia, Romania, Spain, Sardinia and Chile. Today you can find the most beautiful crystals of the mineral in South and Central America.

In Mexico, are sometimes pseudomorphs of silver ( from Zacatecas ) or acanthite ( from Guanajuato ) to Pyrargyrite to find.

Other localities include several regions in Australia, China and Canada; Hokkaido, Honshu and Kyushu in Japan; Carinthia, Salzburg, Styria and Tyrol in Austria, as well as various regions in the United States. Total so far (as of 2012) are approximately 1,300 localities known as.

Crystal structure

Pyrargyrite crystallizes in the trigonal crystal system in the space group R3c ( Raumgruppen-Nr. 161) with the lattice parameters a = 11.04 Å and c = 8.72 Å and six formula units per unit cell.