Johannite

Johannit (also Uranvitriol ) is a rarely occurring mineral from the mineral class of sulfates. It crystallizes in the triclinic crystal system with the chemical composition of Cu [( UO2) | OH | SO4 ] 2 • 8 H2O and developed only small, prismatic crystals up dicktafelige, but usually scaly or crusty low one aggregates and coatings in grass-green color.

Special Features

Due to the high content of radioactive uranium, the mineral has a non- negligible specific activity. With a mass of one gram of the mineral, this is 87 501 Bq / g (compared to natural potassium 31.2 Bq / g). Due to the natural isotope composition of the uranium which corresponds to an equivalent dose of 12.4 mSv / h per gram of mineral.

Etymology and history

Was first described in 1830 by Johannit Haidinger. It was named after Archeduk John of Austria (1782-1859), the founder of Steiermarker Landesmuseum Joanneum ( Austria ).

Classification

According to the old ( 8th edition ) and new classification of minerals ( 9th Edition ) by Strunz the Johannit is associated with the sulfates. However, while the old system, the mineral nor to the Department of " hydrous sulfates with foreign anions " counts, the class of sulfates in the new classification was restructured and finely divided, so that the Johannit now belongs to the Uranylsulfaten with medium-sized cations.

The classification of minerals according to Dana assigns the Johannit also the mineral class of sulphates, there, however, in the department of " Hydrated Sulfates Containing hydroxyl or halogen where ( A1 B2 ) 3 ( XO4 ) 2 Zq · x (H2O) " (translated: hydrous sulfates which hydroxyl groups or halogens in the group [ ... ] included).

Education and Locations

Johannit forms as a secondary mineral by oxidation of uraninite along with various other uranium minerals

Locations include Mendoza in Argentina; Johann George Town and in the Erzgebirge (Saxony), in the Black Forest (Baden- Württemberg ) and Gera ( Thuringia) in Germany; Brittany, Languedoc -Roussillon, Limousin and Rhone -Alpes in France; Skin Ogooué in Gabon; Attica in Greece; Cornwall (England) in the UK; Trentino -Alto Adige in Italy; Canton of Valais in Switzerland; Jáchymov ( German: Joachimsthal ) in the Czech Republic; as well as Arizona, Connecticut, California, New Mexico, Utah in the United States.

Crystal structure

Crystallizes in the triclinic crystal system Johannit in the space group with the lattice parameters a = 8.92 Å, b = 9.59 Å, c = 6.84 Å; α = 110 °, β = 111.983 °, γ = 100.3 ° and one formula unit per unit cell.