Curite

Curit is a rarely occurring mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the orthorhombic crystal system with the chemical composition Pb3 [( UO2) 4 | O4 | (OH ) 3] 2.2 H2O and usually develops granular to massive or earthy mineral aggregates or crusty coatings, rarely acicular crystals of yellow-orange to red-orange color.

Special Features

The mineral is classified radioactive due to its uranium content of about 63 % as very strong and has a specific activity of about 113.4 kBq / g (compared to natural potassium 0.0312 kBq / g).

Etymology and history

Was first found in the Curit " Shinkolobwe Mine ( Kasolo Mine) " in Katanga in the Democratic Republic of Congo and described in 1921 by Alfred Schoep ( 1881-1966 ). The mineral is named after the physicist and Nobel laureate Pierre Curie ( 1859-1906 ).

Classification

In the old classification of minerals according to Strunz ( 8th edition ) of the Curit still belongs to the joint department of the " uranyl hydroxides and hydrates ". With the revision of Strunz 's Mineral classification in its 9th edition, this department was divided and in addition precisely divided according to the type of the involved cations and the crystal structure. The mineral is now based in the department of " Uranyl Hydroxide " and there only one of his group in the subsection "With additional cations (K, Ca, Ba, Pb, etc.) and mainly UO2 (O, OH) 5 pentagonal polyhedra ".

The commonly used in English-speaking classification of minerals according to Dana assigns the Curit also in the class of oxides and hydroxides, there, however, in the department of " uranium and thorium oxides with a cation charge of 6 , Pb or Bi and some water of hydration or hydroxyl contain ".

Education and Locations

Curit is a secondary mineral that is formed by the weathering of geologically old uraninite. This is due to the formation of lead due to radioactive decay. Curit finally formed in the oxidation zone of ore deposits or in crevices of sedimentary rocks. Accompanying minerals include Dewindtit, Fourmarierit, Kasolit, Rutherfordin, Schoepit, Soddyit, Sklodowskite, Torbernite and Vanden Dries log.

Curit was in addition to its type locality " Shinkolobwe Mine ( Kasolo Mine) " in the Democratic Republic of Congo worldwide so far (as of 2009) been established at around 50 localities, as in any of these " Dara - To Swassi " in the north-eastern desert by the Red Sea in Egypt; Northern Territory of Australia; Baden- Württemberg, Bavaria, Rhineland -Palatinate and Saxony in Germany; Auvergne, Brittany, Alsace and Limousin in France; Lombardy and Trentino -Alto Adige in Italy; in the Northwest Territories of Canada; in Fianarantsoa in Madagascar; Aust- Agder and Telemark in Norway; in the Russian region of Karelia; Namaqualand in South Africa; Bohemia and Moravia in the Czech Republic; in the Hungarian counties of Baranya and Heves and in the U.S. regions Colorado, New Hampshire and New Mexico.

Crystal structure

Curit crystallizes in the orthorhombic space group Pnam ( Raumgruppen-Nr. 62) with the values ​​determined from the year 2000 in several measurements lattice parameters of about a = 12.56 Å; b = 13.02 Å and c = 8.40 Å and two formula units per unit cell.

The crystal structure consists of layers of edge-and corner-sharing uranyl polyhedra, with the uranyl cation both pentagonal- bipyramidal and square- bipyramidal ( octahedral ) coordination has. The lead atoms combine these layers by coordination of the uranyl oxygen atoms.

Precautions

Due to the strong radioactivity of the mineral Specimens of Curit should be stored in a dust - and radiation- proof containers, especially but never in living, sleeping and working areas. Should be definitely prevented and the safety of direct body contact and worn when handling the mineral mask and gloves also because of the high toxicity and radioactivity of uranyl inclusion in the body ( incorporation, ingestion).