Vesuvianite

• Vesuvian
• Idocrase
• Jewreinowit

Vesuvianite (formerly Vesuvian short ), also called Idocrase or Jewreinowit, is a rarely occurring mineral from the mineral class of " silicates and Germanates ". It crystallizes in the tetragonal crystal system having a chemical composition (Ca, Na) 19 (Al, Mg, Fe) 13 ( SiO 4 ) 10 ( Si2O7 ) 4 ( OH, F, O) 10 and developed short prismatic to columnar or tabular crystals, but also, radial, granular, massive aggregates in green, yellow, light blue, purple or brown in color. Even colorless crystals are known.

Special Features

Due to changing, chemical composition shows vesuvianite large variations in its physical properties. On various occasions also weak pleochroism is observed, which varies from yellow to almost colorless and brown crystals from yellow to brown and light brown with green crystals between yellow-green and yellow-brown, with yellow crystals.

Etymology and history

For the first time as a separate mineral vesuvianite was recognized in 1795 by Abraham Gottlob Werner. He named it after the only then known locality, the Vesuvius in Italy, the matter is also considered the type locality. A first detailed chemical analysis was conducted by Martin Heinrich Klaproth through. He also recognized the correspondence with a ( a zirconium variety) by Erich G. Laxmann 1790 found in Siberia and Hyacinth held mineral sample. A second term is Idocrase (Greek "mixed form " ) as a reference to his mixed crystal forms.

Modifications and varieties

• Californit - green, is often mistakenly referred to as a Vesuvian - Jade
• Cyprin - sky blue variety from Norway
• Duparcit - potassium - and iron-rich variety from Morocco, named after Louis Duparc
• Egeran - Brownish columnar variety that has been appreciated by Johann Wolfgang von Goethe as a mineral.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the vesuvianite belonged to the general ward of the "Group silicates ( Sorosilikate ) ", where he was named. , The " Vesuvianitgruppe " with the System No. Formed VIII/C.26 and the other members Flurvesuvianit, Manganvesuvianit and Wiluit.

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the vesuvianite also in the department of " group silicates ( Sorosilikate ) " a. However, this is precisely divided according to the type of silicate complexes occurring in the compound and the coordination of the cations involved, so that the mineral according to its composition in the subsection " group silicates with mixed SiO4 and Si2O7 groups; Cations " is to find out where he is also the " in octahedral coordination and greater Vesuvianitgruppe "with the system no. 9.BG.35 forms.

The mainly common in English-speaking classification of minerals according to Dana assigns the vesuvianite in the department of the group silicates, there, however, in the subdivision of " group silicates with insular, mixed, individual and larger tetrahedral groups and cations in and higher coordination; Single and double groups (n = 1,2). " Here he is, however, also be found as a name of Vesuvianitgruppe.

Education and Locations

Vesuvianite forms either metamorphic or hydrothermally. Calcium in rich rocks such as skarn, marble or rodingites In rare cases vesuvianite occurs in alkaline igneous rocks. Accompanying minerals include grossular, wollastonite and diopside.

Worldwide, Vesuviant so far (as of 2009) are detected at 960 localities, so any of these Monzoni in Italy, Asbestos / Quebec in Canada, Hazlov in the Czech Republic, Crestmore / California and Franklin / New Jersey in the U.S.

Crystal structure

Vesuvianite crystallized in the tetragonal crystal system in space group P4/nnc ( Raumgruppen-Nr. 126) with the lattice parameters a = 15.678 Å and c = 11.828 Å and two formula units per unit cell.

Use as a gemstone

Since vesuvianite is a mineral of medium hardness and low fission tendency, it is often used as a gemstone. Clear crystals thereby obtained a bevelled edge, cloudy varieties rather a cabochon or made into drum stones.

Because of its color vesuvianite can be confused with demantoid, diopside, epidote, jacinth, peridot or Sinhalit.