Saleeite
Saléeit is a mineral from the Autunitgruppe in the mineral class of phosphates, arsenates and vanadates. It crystallizes in the monoclinic crystal system and has the chemical composition Mg [ UO2PO4 ] 2 • 10H2O.
Pseudotetragonalen the crystals are generally flat tabular shape, and is dominated by the base surface of { 001 }. Saléeit is lemon yellow, yellow-green to olive green, transparent to opaque with waxy luster. The stroke color is yellow white. The density is 3.27 g/cm3 and the Mohs hardness is between 2 and 3
Special Features
The mineral is classified highly radioactive due to its uranium content of up to 51 % by weight as and has a specific activity of about 91.2 kBq / g (compared to natural potassium 31.2 Bq / g).
As with the structurally related minerals Torbernite and Zeunerite the water content may vary and Saléeit readily converts into the water- poor mineral Metasaléeit to.
Etymology and history
Was first described in 1932 by J. Thoreau mineral and JF Vaes in silicate rocks from the Shinkolobwe mine in Kasolo in the Katanga Province in the Congo. They named this new mineral by Achille Salee (1883-1932), professor of geology at the Catholic University of Leuven in Belgium.
The type of mineral is located at the Catholic University of Leuven in Belgium.
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz the Saléeit belonged to the mineral class of " phosphates, arsenates and vanadates " and then to the Department of " Uranylphosphate and Uranylvanadate " where he along with Autunit, Fritz log, Heinrichit, Kahlerit, Metanatroautunit, Nováčekit, Sabugalit, 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 Saléeit also in the class of " phosphates, arsenates and vanadates " and there in the department of " Uranylphosphate and arsenates " one. This division, however, is now further subdivided by the ratio of Uranoxidkomplex ( UO2) and phosphate or Arsenatkomplex ( 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 together with Autunit, Heinrichit, Kahlerit, Kirchheimerit, Nováčekit -I, Nováčekit -II, Torbernite, Uranocircite I, II Uranocircite, Uranospinite, Xiangjiangit and Zeunerite the unnamed group 8 EB.05 forms.
The mainly common in English-speaking classification of minerals according to Dana assigns the Saléeit in the class of " phosphates, arsenates and vanadates ", There, however, in the department of " water -containing phosphates, etc. ". Here he is the only member of the unnamed group 40.02a.11 within the sub-division of " water -containing phosphates, etc., with A2 ( B2 ) 2 ( XO4 ) • x (H2O), with (UO2 ) 2 "
Education and Locations
Saléeit forms secondary to the weathering of uranium minerals in the oxidation zone of uranium-bearing hydrothermal and sedimentary deposits.
In the Shinkolobwe mine in Kasolo in the Katanga Province in the Congo Saléeit occurs together with Torbernite and Dewindtit. In the uranium deposit at Schneeberg in Saxony Saléeit is associated with uranophane and Zeunerite.
Worldwide, Saléeit so far (as of 2010 ) can be detected at about 80 localities, so including Australia, Brazil, Germany, France, Italy, Canada, the Democratic Republic of the Congo, Austria, Portugal, Slovenia, Spain, Czech Republic, Hungary, Uzbekistan, the United Kingdom ( UK) and the United States of America (USA).
Morphology
Saléeit forms peudotetragonale rectangular to square crystals with tabular to bladed habit. Tabular crystals show besides the dominant base area { 001 } nor the faces {100 }, { 120 } and { 012 }.
Crystal structure
Saléeit crystallizes in the monoclinic space group P21 / c.
The structure characterized by uranyl phosphate layers that are parallel to the (001 ) plane. The tetrahedral phosphate anion ( PO43 - ) coordinates thereby about its four oxygen atoms of four uranyl ion ( UO22 ), so that for this in each case results in an octahedral coordination by oxygen atoms, the peak of this octahedron representing uranyl oxygen atoms. This linkage pattern gives uranyl phosphate layers between which the water molecules and magnesium ions ( Mg2 ) are located. Each Mg2 is surrounded by six water molecules octahedrally. The remaining four water molecules are directly bound to any cation. However, they contribute to a complex system of hydrogen bonds to a balanced distribution of charges and thus to stabilize the structure.
Layer structure of Saléeit in the direction of the crystallographic c- axis ( __ U __ O __ P __ Mg __ H2O)
Precautions
After contact with Saléeit the hands should be washed to prevent accidentally orally take the radioactive mineral in the body.