Rheniite

• IMA 1999 - 004a

Rheniit is a very rarely occurring rhenium mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the triclinic crystal system with the chemical composition ReS2 and develops rarely millimeter-sized, plate - to flake crystals of silver-white to gray in color and black stroke color to shine through reddish in thin layers. The vast majority of Rheniitfunden consists of granular to massive aggregates. By substituting Rheniit can a certain proportion of molybdenum instead of rhenium (up to 6 wt%).

Special Features

Since the contained in the compound Rheniumisotop 187Re is weakly radioactive, and the Rheniit is slightly radioactive with a specific activity of about 758.7 Bq / g (compared to natural potassium 31.2 Bq / g).

Etymology and history

Rheniit is the only previously known Rheniummineral. First discovered it in 1992 at the fumaroles of Kudriavy volcano on the Kurileninsel Iturup (Russia) and described by MA Korzhinsky, SI Tkachenko, KI Shmulovich, YA Taran and GS Steinberg, the named the mineral after its main component, the element rhenium. Since 2004 Rheniit is recognized by the International Mineralogical Association (IMA ) as a separate mineral ( IMA1999 - 004a ).

Classification

In the old classification of minerals according to Strunz ( 8th edition ) of the Rheniit belongs to the department of " sulfides and sulfosalts with the molar ratio of metal: sulfur, selenium, tellurium <1: 1". Since the revision of the Strunz'schen Mineral classification in the 9th edition of the class of sulfides has been partially re-divided and subdivided according to the precise composition. The mineral is now appropriately in the department of " metal sulfides with the molar ratio M ( etal ): S ( chwefel ) ≤ 1: 2" and there only one of its group in the subsection "M: S = 1: 2, with iron ( fe), Co ( cobalt ), Ni ( lid ), PGE (platinum - group elements ), etc. ".

The more commonly used in English-speaking classification of minerals according to Dana sorted the Rheniit in the department of " sulfides - including selenides and tellurides - with the general composition AmBnXp, with (m n): p = 1: 2" and there in the only member the unnamed group " 02:12:18 ".

Education and Locations

Rheniit forms at temperatures of 500 to 570 ° C in acidic volcanic gases in fumaroles or excretion from the gas phase at temperatures below 400 ° C in porphyry copper and molybdenum deposits.

So far, the mineral could be detected except at its type locality Iturup ( Kudriavy Volcano ) even at four other localities: In the " Phoenix Mine" at Francistown in Botswana, Fortaleza de Minas / Minas Gerais in Brazil, on Usu on the Japanese island of Hokkaido and in a porphyry Cu-Mo deposit in northeastern Greece

Crystal structure

Rheniit crystallizes in the triclinic space group P1 ( Raumgruppen-Nr. 2) with the lattice parameters a = 6.47 Å; b = 6.368 Å; c = 6.401 Å; α = 105 °; β = 91.59 ° and γ = 118.9 °, and four formula units per unit cell.