Allargentum

Allargentum is a rarely occurring mineral from the mineral class of sulfides and sulfosalts and at a maximum silver content of about 99 % silver by native silver, the mineral with the highest silver content. It crystallizes in the hexagonal crystal system having a chemical composition (Ag, Sb) and forms with silver complex adhesions and small grains of a silver-gray to pale yellow color.

Special Features

Allargentum and Dyscrasite form a solid solution series.

Etymology and history

The mineral was first found in 1949 by Paul Ramdohr in cobalt in the Canadian province of Ontario. He defined Allargentum as hexagonal phase in the synthetic system silver - antimony. W. L. Petruk, L. J. Cabri, D.C. Harris, J. M. Stewart and LA Clark but were able to show that the sample Ramdohr used is a mercury and antimony-containing Silbervarietät. Instead, they named one of them also found in Cobalt silver -antimony mineral named Allargentum. This redefinition was also recognized by the IMA.

Classification

In the classification by Strunz Allargentum is counted among the alloys and alloy- like compounds, a subset of the sulfides and sulfosalts. After the 8th edition forms a group together with Dyscrasite. In the 9th edition, it forms its own sub-group of compounds of semi-metals with copper, silver and gold.

In the classification by Dana it forms with Dyscrasite a subset of the sulfides - tellurides and selenides, including - with the composition AmBnXp, with a ratio of (m n) for p of 3:1.

Education and Locations

Allargentum forms in silver -antimony ores. It is associated with silver, Dyscrasite, Breithauptit, Domeykite, Kutinait and stephanite.

Locations are in addition to the type locality in Canada Catamarca and Cordoba in Argentina, Broken Hill and Mount Isa in Australia, Lishu in China, Benešov and Kutná Hora in the Czech Republic, Ylivieska in Finland, Bad Schlema in Germany, Narsaq to Greenland, Qostanai in Kazakhstan, Karasjok, Porsanger and Hemnes in Norway, Dalnegorsk in Russia, several mines in Sweden, Adrasman in Tajikistan and Ouray in the U.S. state of Colorado. Overall Allargentum could be detected at over 40 sites worldwide to date.

Crystal structure

Allargentum crystallizes in the hexagonal crystal system in space group P63/mmc with lattice parameters a = 2.94 Å and c = 4.78 Å and two formula units per unit cell.