Bromargyrite

• Bromite
• Bromspat
• Bromyrit
• Silver bromide or silver

Bromargyrit, also known as bromite, bromide, or Bromspat Bromyrit, is a rarely occurring mineral from the mineral class of halides. It crystallizes in the cubic crystal system with the chemical composition of AgBr.

Bromargyrit is transparent to translucent and develops cubic crystals of up to one centimeter in size with diamond-like gloss to the surfaces which are arranged in parallel groups. Often it is also found in the form of coarse masses or wax - up horn -like, crusty coatings. The color of the mineral varies from light yellow and olive green, often with a brownish or gray down.

Special Features

When exposed to light, the mineral discolored brown or black due to the formation of elemental silver. On the air Bromargyrit can spread a strong odor of " medicines".

With an average Mohs hardness of 2 Bromargyrit belongs to the soft minerals, which can be similar to the reference minerals gypsum or halite scratched with a fingernail. In contrast to these rather brittle minerals Bromargyrit is extremely malleable and can be cut with a knife.

Before the blowpipe Bromargyrit is easily fusible. In acids it hardly ever dissolves in ammonia, however.

Etymology and history

The mineral was named after its composition, the elements bromine and silver (Greek ἄργυρος [ argyros ] and latin argentum ).

Bromargyrit was first discovered by Pierre Berthier in Plateros in the Mexican state of Zacatecas. The local miners referred to this as a silver ore Plata verde ( German: green silver).

Scientifically described and named the mineral (the analysis was carried out by Carl Friedrich Plattner ) was in 1849 by August Breithaupt.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Bromargyrit belonged to the general ward of a "Simple halides ," where he " halite series" with the along with Carobbiit, Chlorargyrite, Griceit, halite, sylvite and Villiaumit System no. III/A.01 formed.

The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the Bromargyrit into the already fine divided department of a "Simple halides, without H2O". This is also subdivided in accordance with the molar ratio of metal (M) to the respective connected thereto, halogen (X ), so that the mineral according to its composition in the subsection "M: X = 1: 1 and 2: 3 " can be found, where it only together with Chlorargyrite the " Chlorargyritgruppe " with the system no. 3.AA.15 forms.

The mainly common in English-speaking classification of minerals according to Dana assigns the Bromargyrit into the class / department of " halides ". Here he is with Chlorargyrite and Embolit in the " Embolitgruppe " with the system no. 09:01:04 to find " water clear and hydrated halides with the formula AX" within the subdivision of.

Modifications and varieties

Bromargyrit ( AgBr ) forms a complete mixed batch with Chlorargyrite ( AgCl), the intermediate members or mixed crystals as Bromchlorargyrit or Embolit (Ag (Br, Cl) ) are referred to. Boron and iodine-containing Bromargyrit is also very common. Also referred to as iodinated Embolit Jodobromit (Ag (Br, Cl, I) ).

Education and Locations

Bromargyrit is found as a secondary mineral predominantly in the oxidation zone of silver deposits and forms especially under arid, ie dry climate conditions. In addition to native silver occur, you still Jodargyrit, Smithsonite and various iron -manganese oxides as accompanying minerals.

As a rather rare mineral formation Bromargyrit can indeed be abundant in part to different sites, overall it is not very common. So far (as of 2012) are regarded as known a little more than 200 localities. Apart from its type locality Plateros the mineral occurred yet in many other mines in Zacatecas and other Mexican states.

In Germany Bromargyrit found among others in the pits "Clara" and "Fortuna" at Oberwolfach in Baden- Württemberg, near Bad Ems and in the pit " Beautiful view " in Dernbach in Rhineland -Palatinate, in the Mansfeld Basin, Saxony- Anhalt and in the pit " Sauberg " in honor Friedersdorf in the Saxon Erzgebirge.

Other localities lie among others in Argentina, Australia, Bolivia, Chile, China, France, Italy, Morocco, New Zealand, Russia, Spain, the Czech Republic, Hungary, in the U.S. Virgin Islands and the United States of America.

Crystal structure

Bromargyrit crystallizes in the cubic crystal system in the space group Fm3m ( Raumgruppen-Nr. 225 ) with the lattice parameters a = 4.77 Å and four formula units per unit cell.

Use

Bromargyrit is an ore for the production of elemental silver.