Autunite
Autunit (also Kalkuranglimmer ) is a commonly occurring mineral from the mineral class of " phosphates, arsenates and vanadates ", which belongs to the group of uranium mica. It crystallizes in the tetragonal crystal system with the chemical composition Ca [ UO2 | PO4 ] 2 · 10H 2 O and usually develops tabular, book-like crystals, but also flaky or scaly aggregates in bright yellowish, yellow-green or green with light yellow stroke color.
Special Features
The mineral is classified radioactive due to its uranium content to be very strong and has a specific activity of about 86 kBq / g (compared to natural potassium 31.2 Bq / g).
Under UV light shows Autunit a strong, yellowish green fluorescence, similar to that of neon-colored highlighters.
Etymology and history
Was first found Autunit 1852 in the French town of Saint -Symphorien -de- Marmagne near the town of Autun. Was scientifically described the mineral by the two British crystallographer and mineralogist Henry James Brooke (1771-1857) and William Hallowes Miller (1801-1880), who named it after its type locality.
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz the Autunit belonged to the mineral class of " phosphates, arsenates and vanadates " and then to the Department of " Uranylphosphate and Uranylvanadate " where he along with Fritz log, Heinrichit, Kahlerit, Metanatroautunit, Nováčekit, Sabugalit, Saléeit, Torbernite, Trögerit, Uranocircite, Uranospinite and Zeunerite formed a distinct group.
The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the Autunit also in the class of " phosphates, arsenates and vanadates " and there in the department of " Uranylphosphate and arsenates " one. This division, however, is further subdivided by the ratio of Uranoxidkomplex (UO2 ) for phosphate, arsenate or Vanadatkomplex ( RO 4 ), so that the mineral according to its composition in the subsection " UO2: RO 4 = 1:1, Autunit family: [( UO2) - RO 4 ] documents " is to find where it is named as the " Autunitgruppe "with the system no. 8.EB.05 and the other members Heinrichit, Kahlerit, Kirchheimerit (H ), Nováčekit -I, Nováčekit -II, Saléeit, Torbernite, Uranocircite -I, Uranocircite -II, Uranospinite, Xiangjiangit and Zeunerite forms.
The mainly common in English-speaking classification of minerals according to Dana assigns the Autunit in the class of " phosphates, arsenates and vanadates " and there in the department of " water containing phosphates, etc. " field. He is also named as the " Autunitgruppe " with the system no. 40.02a.01 and the other members of meta- autunite, Pseudo - autunite and Metanatroautunit within the sub-division of " water -containing phosphates, etc., with A2 ( B2 ) 2 ( XO4 ) × x (H2O), with (UO2 ) 2 " to find.
Education and Locations
Autunit is formed by oxidation in uranium deposits and pegmatite. Similarly, it may be sedimentary or hydrothermal form in various other uranium ores.
Could Worldwide Autunit so far (as of 2011) are detected at almost 1100 localities. Apart from its type locality Autun in Burgundy, the mineral in France include the region of Aquitaine, Alsace, Auvergne, Brittany, Languedoc -Roussillon, Limousin, Lorraine, Midi -Pyrénées, Pays de la Loire, Poitou -Charentes, was the Provence- Alpes- Côte d' Azur and Rhône -Alpes found.
In Germany Autunit before and at several locations in the Black Forest in Baden- Württemberg, at the Hard Koppe at Sailauf in the Spessart, in Schwandorf and at several places in the Fichtelgebirge, the Bavarian and Upper Palatinate Forest in Bavaria, the Erzgebirge and Vogtland in Saxony and in Wurzbach the former Absetzerhalde at Ronneburg found in Thuringia. Unusually large crystals up to 3 cm in diameter, were known here, especially from the Fund areas Johann George Town and Schneeberg.
In Austria, the mineral was previously the Milstätter lake and near Villach in Carinthia; Raurisertal and on Mitter mountain in the Berchtesgaden Alps in Salzburg and in the Fischbacher Alps and the Kor in Styria.
Other localities lie among others in Argentina, Australia, Belgium, Bolivia, Brazil, Chile, China, Finland, Italy, Japan, Kazakhstan, Madagascar, New Zealand, Pakistan, Poland, Portugal, Rwanda, Romania, Russia, Spain, Slovakia, Slovenia, South Africa, Tajikistan, the Czech Republic, Hungary, Uzbekistan and the United Kingdom ( UK) and the United States of America (USA).
Crystal structure
Autunit crystallizes in ditetragonal - dipyramidalen crystal system in the space group I4 / m mm with the lattice parameters a = 7.009 Å and c = 20.736 Å and two formula units per unit cell.
Security measures
Due to the high radioactivity of the mineral samples should be stored in a dust - and radiation- proof 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.