Nosean

• Spin Ellan

• Na8 [ SO4 | Al6Si6O24 ] · H2O
• Na8 [ SO4 | ( AlSiO4 ) 6]

Nosean is a rarely occurring mineral from the mineral class of " silicates and Germanates ". It crystallizes in the cubic crystal system with the chemical composition Na8 [ SO4 | Al6Si6O24 ] · H2O, is thus seen chemically a hydrous sodium aluminosilicate with sulfate ions as additional anions.

Nosean usually develops only small, dodecahedral crystals to about two millimeters in size, but also comes in the form of granular to massive mineral aggregates before. In its pure form it is colorless and transparent. But it can also appear white and accept by foreign admixtures a blue, green or gray-brown to black color by multiple refraction due to lattice defects or polycrystalline training, the transparency decreases accordingly.

Nosean and Haüyn form a complete mixed batch.

Special Features

Reiner nosean is colorless. However, it may be due to lattice defects, microcrystalline training or twinning and high light scattering associated with a white to gray. Through foreign admixtures of potassium and iron or partial replacement of the [ SO4 ] 2 - complex by the mineral Cl can also assume a bluish, greenish or brownish color.

Etymology and history

Was first discovered nosean on the clamp head at Brenk in the Rhineland-Palatinate Eifel and described in 1808 by Karl Wilhelm Nose, who described the mineral as a spin Ellan, because he considered it a of the spinel related mineral.

1815 could refute the suspected relationship with the spinels Martin Heinrich Klaproth by more detailed analysis. He therefore suggested to rename the mineral and ( first in first publication Nosian ) to denote after its describer as nosean.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the nosean belonged to the department of " framework silicates ( tectosilicates ), with zeolites ", where he along with Bicchulith, Haüyn, hydrosodalite, Kamaishilith, Lazurite, Sodalite, tsaregorodtsevite and Tugtupite the " sodalite series" with the system no. VIII/J.11 formed.

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the nosean in the fine already divided the department " framework silicates ( tectosilicates ) without zeolitic H2O" one. This is also further divided according to the possible presence of other anions, so that the mineral is found according to its composition in the subsection " framework silicates ( tectosilicates ) with additional anions ," where it along with Bicchulith, Danalith, Genthelvin, Haüyn, Helvin, Kamaishilith, lazurite, sodalite, tsaregorodtsevite and tugtupite the " sodalite Danalith group " with the system no. 9.FB.10 forms.

The mostly commonly used in English-speaking classification of minerals according to Dana assigns the nosean likewise in the Department of framework silicates, there, however, in the subdivision of " framework silicates with Al- Si lattice, feldspar and related species ", where he, together with sodalite, Haüyn, lazurite, Bicchulith, Kamaishilith, tugtupite and tsaregorodtsevite in the " Sodalitgruppe " can be found.

Modifications and varieties

Ittnerit ( ash- gray to blue ) and Skolopsit (light gray to fleischrot ) are two zeolitic in different degrees Noseane and are considered varieties of this.

Education and Locations

Nosean formed in silicon- poor, alkaline igneous rocks such as the phonolite. Here, it passes among others in paragenesis with sanidine, on different mica, leucite, magnetite, ilmenite, titanite and zircon.

A rare mineral formation nosean could be detected only in a few localities, where so far (as of 2013) are about 60 localities known as. Apart from its type locality Schell head the mineral in Germany could still be found, such as, among others, in the territory of the Laacher See and Mendig in Rhineland -Palatinate and in Horberig near Oberbergen and the cat's back in Baden- Württemberg in many other places in the Eifel.

The only known locality in Austria is the Stradner Kogel in the southeastern Styria and so far the only Swiss locality is the Reiat region in the canton of Schaffhausen.

Other localities include the lapis lazuli deposit " Ladjuar Medam " in Sar -e -Sang in Afghanistan, Antarctica, the Huon Valley Municipality in Tasmania (Australia), some places in the French department of Cantal, Cape Dalton and Kangerlussuaq in Greenland, Los Archipelago in Guinea, some find points in the Italian region Latium, the volcanic cone Etinde on Mount Cameroon in Cameroon, Labrador and Montreal in Canada, Centurion in the department of Concepción in Paraguay, the Chibinen on the Russian Kola Peninsula, Särna in the Swedish province of Dalarna County, the High Park in the Jizera Mountains in the Czech Republic, at the Wolf Rock in the English community Sennen in the United Kingdom ( UK), and several places in various states of USA.

Crystal structure

Nosean crystallized cubic in space group P43n ( Raumgruppen-Nr. 218 ) with the lattice parameters a = 9.08 Å, and one formula unit per unit cell.