Carnotite

Carnotite is a commonly occurring mineral from the mineral class of " oxides and hydroxides " (formerly phosphates, arsenates and vanadates ). It crystallizes in the monoclinic crystal system with the chemical composition K2 [ UO2 | VO4 ] 2 • 3H2O and usually develops massive or earthy mineral aggregates, but rarely also tabular to acicular crystals to about 2 mm in size from light to dark green or yellow-green color with light yellow stroke color.

Special Features

The mineral is classified as very highly radioactive due to its uranium content of up to 52.8 % and has a specific activity of about 94.46 kBq / g (compared to natural potassium 31.2 Bq / g).

Carnotite is often difficult to distinguish from other uranium minerals; occasionally X-ray structural analyzes are necessary for this.

Etymology and history

Carnotite was first discovered in the " Rajah Mine" at Uravan in Montrose County ( Colorado) in the U.S. and described in 1899 by Charles Friedel and Edouard Cumenge who named the mineral after the French chemist Marie Adolphe Carnot.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the carnotite belonged to the mineral class of " phosphates, arsenates and vanadates " and then to the Department of " Uranylphosphate and Uranylvanadate " where he along with Curienit, Francevillite, Margaritasit, Metatyuyamunit, Metavanuralit, Sengierit, Strelkinit, Tyuyamunite and Vanuranylit formed a distinct group.

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of Strunz 's Mineral classification assigns the carnotite contrast, in the class of " oxides and hydroxides " and there in the department of " V [ 5,6] vanadates, " a. This department is also further divided according to the crystal structure, so that the mineral is found in accordance with its construction in the subsection " uranyl Gruppenvanadate ( Sorovanadate ) ", where it forms the unnamed group 4.HB.05 only together with Margaritasit.

The mostly commonly used in English-speaking classification of minerals according to Dana assigns the carnotite as the outdated Strunz'sche systematics in the class of " phosphates, arsenates and vanadates " one -up, but in the department of " water -containing phosphates, etc. ". Here he is with Margaritasit in the unnamed group 40.02a.28 within the sub-division of " water -containing phosphates, etc., with A2 ( B2 ) 2 ( XO4 ) × x (H2O), with (UO2 ) 2 " to find.

Education and Locations

Carnotite formed by deposition in vanadium and uranium- rich waters as a sedimentary rock. Accompanying minerals include Tyuyamunite, Metatyuyamunit, Volborthit, Tangeite, Metatorbernite, Rossit, Hewettit and other uranium and vanadium oxides and gypsum and barite.

Worldwide, carnotite so far (as of 2011) are detected at around 1100 localities. Important deposits are located in the U.S. state of Colorado, in Namibia ( Langer Heinrich mine ) as well as in Morocco. Other localities include Democratic Republic of the Congo, Colorado and Utah in the United States, as well as Tyuya Muyun in Uzbekistan.

Crystal structure

Carnotite crystallizes in the monoclinic space group ( Raumgruppen-Nr. 14) with the lattice parameters a = 10.47 Å; b = 8.41 Å; c = 6.59 Å and 103.8 ° and β = 2 formula units per unit cell.

Use

The high uranium dioxide content of 63 percent, which is responsible for the radioactivity of the mineral, it makes a significant uranium and Vanadiumerz.

Security measures

Due to the high radioactivity of the mineral samples should be stored in a dust - and stahlungsdichten containers, especially but never in living, sleeping and working areas. Similarly, inclusion in the body ( incorporation) should be definitely prevented and the safety of direct body contact and worn when handling the mineral mask and gloves