Dyscrasite

• Antimony silver or silver antimony
• Discrase
• Diskrasit
• Spies ( s ) gloss silver or antimony, silver or silver antimony

Dyscrasite, outdated as antimony, silver is a rarely occurring mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the orthorhombic crystal system with the idealized chemical composition Ag3Sb, that is made of silver and antimony in the ratio 3: 1

Dyscrasite rarely develops well -formed crystals with tabular to prismatic, cylindrical or pyramidal habit and striped, shiny metallic surfaces. Also known are pseudo-hexagonal twinning. Usually he can be found, however, in the form of leafy or grained to massive mineral aggregates. Fresh samples are from silver-white to pale yellow in color, however, starts with the lead- time gray to black.

With a Mohs hardness of 3.5 to 4 Dyscrasite belongs to the medium-hard minerals, can be cut with a knife, therefore, despite its brittleness.

Etymology and history

The mineral in 1782 by Torbern Olof Bergman ( 1735-1784 ) was first mentioned under the name Argentum nativum antimonio adunatum

In older German literatures, there Dyscrasite found under various names, including, inter alia 1786 at Bergrath Selb and 1796 with Abraham Gottlob Werner Spies as a gloss silver and 1813 with Friedrich Hausmann Silver Spies shine. A more precise term is replaced by the mineral in 1821 by Karl Caesar von Leonhard and 1823 and by August Breithaupt, the name it after its composition as antimony - silver or silver antimony.

Its up today valid name Dyscrasite derives from the François Sulpice Beudant 1832 coined term Discrase after the Greek word δνσκρᾶσις or better δνσκρασία for " bad mix " from which refers to the varying silver content in the compound.

As a type locality applies the environment of Wolfach due to the chemical analyzes by Martin Heinrich Klaproth and the pit Wenzel at Oberwolfach according to analyzes by G. Markl and J. Otto in 1992 on material found there.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Dyscrasite belonged within the sulfides to the Department of " alloys and alloy-like compounds ", where he led the unnamed group formed together with Allargentum II/A.02.

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the Dyscrasite also in the department of " alloys and alloy-like compounds " one. However, this is further subdivided according to the conditions prevailing in the interconnect metals, so that the mineral according to its composition in the subsection " compounds of semi-metals with copper ( Cu), silver (Ag ), gold ( Au) " can be found, where it acts as single member of the unnamed group forms 2.AA.35.

The mainly common in English-speaking classification of minerals according to Dana assigns the Dyscrasite into the class of " sulfides and sulfosalts " and there in the department of " sulfide minerals ." Here he is as the namesake of the " Dyskrasitgruppe " with the system no. 02:02:01 within the subdivision " sulfides - tellurides and selenides, including - with the composition AmBnXp, with (m n): p = 3:1 " to find.

Education and Locations

Dyscrasite formed in hydrothermally in ore - transitions usually associated with native silver and other silver minerals such as, among others, acanthite, Pyrargyrite and Stromeyerite and other ores such as Allemontite ( mixture of Stibarsen and native arsenic or antimony), barite, calcite, galena and tetrahedrite.

As a rather rare mineral formation Dyscrasite can indeed be abundant in part to different sites, overall it is not very common. So far (as of 2013) are considered to be known around 160 localities. Apart from its type locality pit Wenzel at Oberwolfach, the mineral found in Germany still a few more places in the Black Forest (Baden- Württemberg ) and in Sinatengrün and Lam in Bavaria, in several pits at St. Andrew mountain in Lower Saxony and some places in the Saxon Erzgebirge.

The only known locality in Switzerland is close Böttstein where the mineral was found in a study conducted by the NAGRA hole.

Known for its extraordinary Dyskrasitfunde is especially the uranium deposit Haje u Příbramě in the Czech Příbram, where up to five inches large crystals and twins came to light.

Other localities lie including Australia, Bolivia, Chile, China, Finland, France, Italy, Canada, Kazakhstan, Morocco, Norway, Russia, Sweden, Slovakia, Spain, South Africa, Tajikistan, and in several states of the USA.

Crystal structure

Dyscrasite crystallizes in the orthorhombic space group Pm2m ( Raumgruppen-Nr. 25) with the lattice parameters a = 3.01 Å; b = 5.21 Å and c = 4.83 Å, and one formula unit per unit cell.