Wiluite

• IMA 1997-026

Wiluit is a rarely occurring mineral from the mineral class of " silicate and germanate ". It crystallizes in the tetragonal crystal system having a chemical composition CA19 (Al, Mg, Fe, Ti) 13B <3 [ (O, OH) 10 | ( SiO4) 10 | ( Si2O7 ) 4] and usually is well developed, tetragonal dipyramidal crystals dark green, greenish brown or black color.

Etymology and history

The mineral on the Siberian river Wiljui was first discovered (Russia) and named after the type locality.

Initial descriptions already exist through out the year 1802. In " Textbook of Oryktognosie " by Johann Reinhold Blum of 1833, he is as green garnet and variety of the grossular with asparagus, mountain, grass, olive, leek, pistachio-green or green -gray described to the liver- brown color.

After renewed investigation by LA Groat, FC Hawthorne, T.S. Ercit and J. D. Grice 1998 the mineral recognized by the International Mineralogical Association (IMA ) as a separate mineral.

Classification

In the now outdated nomenclature of minerals by Strunz ( 8th edition ) of the Wiluit still belongs to the general ward of the "Group silicates ( Sorosilikate ) ", where it forms a separate group together with Fluorvesuvianit, Manganvesuvianit and vesuvianite.

Since the revision of the Strunz'schen Mineral classification in the 9th edition also this department is precisely divided according to the type of silicate complexes occurring in the compound and the coordination of the cations involved. The Wiluit is in accordance with the unchanged on associated minerals Vesuvianitgruppe in the new subdivision of the " group silicates with mixed SiO4 and Si2O7 groups; Cations in oktahedraler and greater coordination. "

The commonly used in English-speaking classification of minerals according to Dana assigns the Wiluit also in the Department of the silicates group, however, there in the subdivision of " group silicates with insular, mixed, individual and larger groups and cations in tetrahedral and higher coordination; Single and double groups (n = 1,2) ", where he also, together with Fluorvesuvianit, Manganvesuvianit and vesuvianite own group Vesuvianitgruppe.

Education and Locations

Wiluit was found along with grossular and minerals of the serpentine group in serpentinized skarn.

So far, the mineral was in addition to its type locality Wiljui still at three other localities (as of 2009) are recorded: In the Italian territory Ariccia, in Gatineau in Canada, as well as in the " Bill Waley mine " in Drum Valley ( Tulare County) in the USA.

Crystal structure

Wiluit crystallizes isostructural with vesuvianite in the tetragonal crystal system in space group P4/nnc with the lattice parameters a = 15.716 Å and c = 11.704 Å and two formula units per unit cell.