Hessite

• Tellursilber
• Tellursilberglanz
• Botesit
• Savodinskit
• Hölzel no. 2.BA.600

Hessite, also known as Tellursilber, is a rarely occurring mineral from the group of sulfides and sulfosalts. It crystallizes in the monoclinic crystal system with the chemical composition of silver telluride Ag2Te and constitutes up to 1.7 centimeter, pseudocubic irregularly grown crystals, but also compact masses or fine grains of lead to steel gray color.

Etymology and history

The mineral was first described in 1830 by Gustav Rose. This examined a ore from the Sawodinski mine in the Altai ( Siberia ) came and was exhibited at the museum in Barnaul. There had been kept for argentite. Investigations with the blowpipe and other tests but Rose quickly realized that there must be a silver -tellurium mineral and described it accordingly as Tellursilber.

His final name hessite received the mineral in 1843 by Julius Froebel, who named it after the Swiss- Russian chemist and mineralogist Germain Henri Hess ( 1802-1850 ).

Type material of the mineral is located among others in the mineral collection of the Museum of Natural History in Berlin ( 1999-7528 and 1999-0072 Register-Nr. ).

Classification

Is hessite in the Strunz classification by the sulfides and sulfosalts, which have a ratio of metal to sulfur of greater than 1:1 counted. In the 9th edition of the classification, a further distinction according to the cations here covellite is classified as a sulfide with a ratio of metal to sulfur of 1:1 and contained copper, silver or gold. It forms a separate group. In the 8th edition of the group includes, in addition to Covellite this mineral nor Aguilarit, acanthite, argentite, Benleonardit, Cervelleit, Empressit, Naumannite, Tsnigriit and Stützit.

According to the classification by Dana hessite one of the sulphides with the composition AmBn Xp, with a ratio of (m n) for p of 2:1 and forms with Cervelleit a subgroup.

Modifications and varieties

At a temperature of 155 ° C hessite merges into a cubic form.

Education and Locations

Hessite formed under hydrothermal conditions at low or medium temperatures, and at low levels in pyrite deposits. It is associated with Calaverit, sylvanite, Altait, petzite, Empressit, Rickardit, gold, tellurium, pyrite, galena, tetrahedrite and chalcopyrite.

There are a total of 431 known localities (April 2010 ) of the Hessits. In addition to the type locality include Sacarimb and Zlatna in Romania, Kalgoorlie in Australia, Fiji, Coquimbo in Chile, Canada and the U.S. states of Colorado, California and Arizona to do so.

Crystal structure

Hessite crystallizes in the monoclinic crystal system, space group P21 / c with lattice parameters a = 8.164 Å, b = 4.468 Å, c = 8.977 Å and β = 124.16 °, and four formula units per unit cell.

Use

Due to the high silver content of 63.3 % hessite is a silver ore.